Learn Hardcore Greek: Ο οδηγός ήταν απρόσεκτος και δεν είδε τον πεζό στη διάβαση. - The driver was careless and didn’t see the pedestrian at the crosswalk.

ο οδηγός = nominative singular masculine
- Subject of the sentence → the driver is the one doing the action.
τον πεζό = accusative singular masculine
- Direct object of the verb → the pedestrian is the one being seen (or in this case, not seen).

So:

Subject: ο οδηγός (nominative)
Object: τον πεζό (accusative)

Both nouns are masculine singular, but the article changes to show their function in the sentence.

Why is it πεζό and not πεζός here?

Πεζός is the nominative masculine singular form (dictionary form: ο πεζός = the pedestrian).

In this sentence, the pedestrian is the direct object of the verb είδε (saw), so Greek uses the accusative:

Nominative (subject): ο πεζός
Accusative (object): τον πεζό

Masculine nouns ending in -ός typically change to -ό in the accusative singular:

ο φίλος → τον φίλο
ο δρόμος → τον δρόμο
ο πεζός → τον πεζό

What tense is ήταν? Is it related to είμαι?

Yes. Ήταν is the past tense of the verb είμαι (to be).

είμαι = I am
ήμουν = I was (1st person singular)
ήταν = he/she/it was, or they were (depending on context)

In this sentence:

Ο οδηγός ήταν απρόσεκτος = The driver was careless.

So ήταν here is 3rd person singular past of είμαι.

What tense is είδε, and how is it different from βλέπει or έβλεπε?

Είδε is the aorist (simple past) of βλέπω (to see).

βλέπει = he/she/it sees, is seeing (present)
είδε = he/she/it saw (a completed action in the past)
έβλεπε = he/she/it was seeing / used to see (past continuous or repeated action)

In this sentence:

δεν είδε τον πεζό = did not see the pedestrian (a single, complete event at that moment), so the aorist είδε is the natural choice.

Why is the negation δεν είδε and not something like είδε δεν?

In Greek, the basic pattern for negating a verb in the indicative is:

δεν + verb

So:

είδε = he/she/it saw
δεν είδε = he/she/it did not see

The word δεν almost always goes immediately before the verb (or before any clitics + verb cluster, e.g. δεν τον είδε = he didn’t see him). Putting δεν after the verb is ungrammatical in standard Greek.

What exactly is στη? Is it one word or two?

Στη is a contraction of two words:

σε (preposition: in, at, on, to)
τη (feminine accusative singular article: the)

So:

σε + τη διάβαση → στη διάβαση

This contraction is extremely common in modern Greek:

σε + τη → στη
σε + την → στην
σε + το → στο
σε + τον → στον

In speech and writing, you will almost always see the contracted forms in sentences like this.

Why is it στη διάβαση and not στην διάβαση?

The full (uncontracted) form would be:

σε την διάβαση → στην διάβαση

In modern Greek, στην often becomes στη before many consonants, especially dental consonants (like δ, ν, τ), to make pronunciation smoother. You will hear both στη διάβαση and στην διάβαση; στη διάβαση is common and perfectly correct in everyday usage.

The key point: both are understood; στη here is just the more natural, elided spoken form.

What does the preposition σε (as in στη διάβαση) really mean here?

The preposition σε is very flexible. Depending on context, it can correspond to:

In στη διάβαση, it means something like at or on:

στη διάβαση ≈ at the crossing / on the crosswalk

Greek doesn’t split these meanings into separate prepositions the way English does; σε covers all of them, and context (plus the noun) tells you which English preposition is best.

What gender is διάβαση, and how do I know which article to use?

Διάβαση is feminine.

You can see this from:

its typical feminine noun ending -ση
the article τη in στη (σε + τη) διάβαση

So:

Nominative: η διάβαση (the crossing)
Accusative: τη/την διάβαση → στη διάβαση

Feminine nouns commonly end in -η, -α, or -ση in the nominative singular and take the article η (nominative) / τη(ν) (accusative).

Why is it ήταν απρόσεκτος and not ήταν απρόσεκτη?

The adjective must agree with the gender, number, and case of the noun it describes.

ο οδηγός is grammatically masculine singular.
Therefore, the predicate adjective also appears in masculine singular nominative:
- απρόσεκτος (masculine)
- απρόσεκτη (feminine)
- απρόσεκτο (neuter)

So:

Ο οδηγός ήταν απρόσεκτος. (The driver was careless.)
Η οδηγός ήταν απρόσεκτη. (If the word refers to a female driver and is treated as feminine.)

What does απρόσεκτος literally mean? Is it related to προσεκτικός?

Yes. Απρόσεκτος is formed by adding the negative prefix α- to the adjective προσεκτικός.

προσεκτικός = careful, attentive
απρόσεκτος = careless, inattentive

This α- (sometimes αν- before vowels) often creates the opposite meaning:

λογικός → αλόγιστος (rational → irrational)
πιθανός → απίθανος (probable → improbable)
προσεκτικός → απρόσεκτος (careful → careless)

Why don’t we repeat the subject before δεν είδε? Could we say Ο οδηγός ήταν απρόσεκτος και ο οδηγός δεν είδε…?

You could repeat ο οδηγός, but it would sound heavy and unnatural here.

Greek normally does not repeat the subject when it’s clearly the same as in the previous clause, especially when the clauses are joined with και (and). The subject ο οδηγός is understood to apply to both verbs:

Ο οδηγός ήταν απρόσεκτος και (ο οδηγός) δεν είδε τον πεζό…

In natural Greek:

Ο οδηγός ήταν απρόσεκτος και δεν είδε τον πεζό στη διάβαση.

Could we say δεν είδε πεζό στη διάβαση without the article τον? Would that change the meaning?

Yes, you can drop the article, but the nuance changes:

δεν είδε τον πεζό στη διάβαση
- More specific/definite: He didn’t see *the pedestrian at the crossing.*
  (perhaps a particular, known pedestrian)
δεν είδε πεζό στη διάβαση
- More indefinite or generic: He didn’t see *any pedestrian at the crossing.*

Greek uses the definite article a lot more than English, especially for specific, concrete nouns, so τον πεζό is very natural in this context.