Fīō means “become” or “happen” and also supplies the present-system passive of faciō “make, do.” Its principal parts are fīō, fierī, factus sum. The system is suppletive: present forms use fī-/fie-, while completed forms use agreeing factus, -a, -um plus sum.
Most finite present forms have active-looking endings although their meaning may be passive. Identify the form first; then let its subject and complements choose among “be made,” “become,” and “happen.”
The Suppletive Map
| System | Forms | Possible meanings |
|---|---|---|
| Present | fīō, fierī | am made; become; happen |
| Perfect | factus sum | was made; became; happened |
| Corresponding active | faciō, facere, fēcī, factum | make, do |
Indicative: Complete Paradigm
| Tense | 1st sg. | 2nd sg. | 3rd sg. | 1st pl. | 2nd pl. | 3rd pl. |
|---|---|---|---|---|---|---|
| Present | fīō | fīs | fit | fīmus | fītis | fīunt |
| Imperfect | fīēbam | fīēbās | fīēbat | fīēbāmus | fīēbātis | fīēbant |
| Future | fīam | fīēs | fīet | fīēmus | fīētis | fīent |
| Perfect | factus sum | factus es | factus est | factī sumus | factī estis | factī sunt |
| Pluperfect | factus eram | factus erās | factus erat | factī erāmus | factī erātis | factī erant |
| Future perfect | factus erō | factus eris | factus erit | factī erimus | factī eritis | factī erunt |
The perfect rows use a masculine subject for display. With feminine or neuter subjects write facta/factum in the singular and factae/facta in the plural.
Ex timidō puerō vir fortis fit.
From a timid boy he becomes a brave man.
Pōns novus ā mīlitibus lentē fit.
The new bridge is slowly being built by the soldiers.
Adulēscentēs cotīdiē prūdentiōrēs fīēbant.
The young people were becoming wiser every day.
Haec statua prope templum fīet.
This statue will be made near the temple.
Trēs nāvēs ūnō annō factae erant.
Three ships had been built in one year.
Subjunctive and Imperative
| Tense | 1st sg. | 2nd sg. | 3rd sg. | 1st pl. | 2nd pl. | 3rd pl. |
|---|---|---|---|---|---|---|
| Present | fīam | fīās | fīat | fīāmus | fīātis | fīant |
| Imperfect | fierem | fierēs | fieret | fierēmus | fierētis | fierent |
| Perfect | factus sim | factus sīs | factus sit | factī sīmus | factī sītis | factī sint |
| Pluperfect | factus essem | factus essēs | factus esset | factī essēmus | factī essētis | factī essent |
Future indicative fīam and present subjunctive fīam are identical; syntax distinguishes them. Crās medicus fīam is a future assertion, while pater vult ut medicus fīam places the same form in an ut-clause.
Cūrā ut omnia ante noctem fīant.
See to it that everything is done before nightfall.
Utinam ex tantā discordiā concordia fieret!
If only harmony might arise from such great discord!
The present imperatives are fī, fīte: fī bonus “become good,” fīte parātī “become ready.” The full future imperative is fītō (second- or third-person singular), fītōte (second-person plural), and fīuntō (third-person plural); these forms are (formal/archaic) and rare.
Three Core Meanings
An affected nominative subject and an optional agent in ā/ab + ablative favor the passive “be made/done.” A predicate nominative or adjective favors “become.” Impersonal fit or fit ut favors “happen.”
Sententia ā tribus iūdicibus statim fit.
The decision is made at once by three judges.
Post longam hiemem diēs calidiōrēs fīunt.
After a long winter, the days grow warmer.
Interdum fit ut parva causa magnam īram moveat.
Sometimes it happens that a small cause provokes great anger.
Eō tempore factum est ut omnēs tacērent.
At that moment it happened that everyone fell silent.
English “become” may suggest “into,” but Latin uses a predicate nominative: mīles fit “he becomes a soldier.” The new status agrees with or is equated to the nominative subject.
Agent, Material, and Result
When fīō is the passive of faciō, keep three roles distinct. The thing produced is nominative, a deliberate personal maker takes ā/ab + ablative, and the material commonly takes ex + ablative. A predicate describing what the subject becomes remains nominative instead.
Statua ex marmore ā clārō artifice fit.
A statue is being made from marble by a famous artist.
Here statua is the receiver, ex marmore the material, and ā clārō artifice the personal agent. Compare marmor statua fit “the marble becomes a statue,” where statua is a predicate nominative and no maker is expressed. English speakers may be tempted to insert “into,” but Classical Latin does not add in before this predicate.
Ex parvō vīcō urbs magna facta est.
From a small village, a great city came into being.
The perfect facta est agrees with feminine urbs. Although the English translation is eventive, the visible agreement still controls the Latin form. Always determine whether factus is personal and agreeing or neuter impersonal factum est before translating.
Non-Finite Forms and Defects
| Category | Form/status |
|---|---|
| Present infinitive | fierī |
| Perfect infinitive | factum esse, with agreement |
| Future passive infinitive of faciō | factum īrī, fixed supine + īrī |
| Perfect participle | factus, -a, -um |
| Present participle, gerund, supine | no independent ordinary paradigm |
Legātī novam societātem fierī sentiunt.
The envoys perceive that a new alliance is taking shape.
Dīxit portās ante noctem factās esse.
He said that the gates had been made before nightfall.
For eventive future indirect statement, Latin commonly uses fore ut plus a subjunctive rather than inventing a future participle of fīō: spērat fore ut pāx fīat “he hopes that peace will come about.”
Compounds: Two Patterns
Separate first elements followed by -faciō generally preserve a corresponding passive in -fīō: calefaciō → calefīō “heat → be heated,” patefaciō → patefīō “reveal/open → be revealed/opened.”
Aqua igne calefit, sed adhūc bibī nōn potest.
The water is being heated over a fire, but it still cannot be drunk.
Fully prefixed -ficiō compounds instead form regular passives: efficiō → efficior, cōnficiō → cōnficior. Thus opus cōnficitur means “the task is completed”; cōnfit is not its passive. The distinction is lexical and historical, so learn each compound’s principal parts. See the passive of faciō: fīō.
Parsing Diagnostic
First identify fī-/fie- versus fact-. Next determine tense, mood, person, and participial agreement. Finally inspect the construction: affected subject, predicate complement, or impersonal event. This order prevents active-looking fit from being mistaken for “makes” and prevents every factum est from being translated “was manufactured.”
Common Mistakes
Inventing a regular passive of faciō
❌ Nova lēx ā cōnsule facitur.
Incorrect as the Classical present passive of facio.
✅ Nova lēx fit.
A new law is being made.
Extending fī- into completed time
❌ Portae herī fīērunt.
Incorrect for perfect time — the perfect system uses factus sum.
✅ Portae herī factae sunt.
The gates were made yesterday.
Translating every fit as manufacture
❌ Puer laetus fit, id est puer fabricātur.
Incorrect interpretation — the predicate adjective signals change of state.
✅ Puer laetus fit.
The boy becomes happy.
Ignoring participial agreement
❌ Nāvēs factus sunt.
Incorrect — factus must agree with feminine plural nāvēs.
✅ Nāvēs factae sunt.
The ships were built.
Key Takeaways
- Fīō, fierī, factus sum combines present fī-/fie- with perfect fact-.
- Active-looking present endings can carry passive meaning.
- Construction distinguishes “be made,” “become,” and “happen.”
- Perfect forms require participial agreement; impersonal “it happened” uses neuter factum est.
- Compounds in -faciō and -ficiō do not form their passives in the same way.
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Start learning Latin →Related Topics
- Malo: To PreferA2 — A complete reference for mālō, including its irregular present, comparison patterns, softened subjunctives, and defective forms.
- Facio: To Do or MakeA2 — A complete reference for faciō, its active stems, suppletive passive fīō, result predicates, causation, and compounds.
- FioB1 — Conjugate fīō across its suppletive system and distinguish ‘be made,’ ‘become,’ and ‘happen’ from the active meanings of faciō.
- The Passive of Facio: FioB1 — Use fīō for the present-system passive of faciō, distinguish ‘be made,’ ‘become,’ and ‘happen,’ and return to factus sum in the perfect system.
- Facio plus Infinitive and CausationC1 — Recognize the marked Classical faciō-plus-infinitive causative and choose accurately among infinitive, ut-clause, predicate, and more specific causative verbs.