U ponedjeljak imamo ručak s obitelji.

In time expressions with days and hours, Croatian uses u + accusative to mean “on/at” a specific point in time:

• u ponedjeljak = on Monday
• u dva (sata) = at two o’clock

Use na for events or occasions:

• na ručku = at (the) lunch
• na koncertu = at a concert

So U ponedjeljak is the standard way to say “On Monday.”

Because with specific days, u takes the accusative. For inanimate masculine nouns like ponedjeljak, the accusative equals the nominative, so the form doesn’t change: ponedjeljak.

The locative form (ponedjeljku) would literally mean “in Monday” and isn’t used for scheduling. You’ll hear locative after u for months (e.g., u siječnju = in January), but not for days of the week.

Yes. Croatian allows flexible word order. Common variants:

• U ponedjeljak imamo ručak s obitelji. (emphasizes the time)
• Imamo ručak s obitelji u ponedjeljak. (more neutral)
• S obitelji imamo ručak u ponedjeljak. (emphasizes “with the family”)

All are correct; the difference is nuance and emphasis.

• Imamo ručak = “we have (a) lunch,” often used for a scheduled or social event (e.g., a planned lunch with someone).
• Ručamo = “we are having lunch / we lunch,” focusing on the act of eating, either right now or habitually.
• Jedemo ručak = “we’re eating lunch (now).” It’s fine, but ručati is more idiomatic for the act.

For a planned meetup, imamo ručak s obitelji usually sounds best.

After s (“with”), Croatian uses the instrumental case. Obitelji here is instrumental singular: “with (the) family.”

Helpful forms of obitelj (family):

• Nominative sg: obitelj
• Genitive sg: obitelji
• Instrumental sg: obitelji (used after s: s obitelji)
• Nominative pl: obitelji
• Instrumental pl: obiteljima (with families: s obiteljima)

Note that several forms look the same; context and the preposition tell you which case it is.

General rule:

• Use s before vowels and most consonants: s obitelji, s Ivanom, s ocem.
• Use sa before words starting with s, z, š, ž, or with awkward clusters, to ease pronunciation: sa sestrom, sa školom, sa ženom, sa psom.

Because obitelji starts with a vowel, s obitelji is the standard form. You may hear sa obitelji, but s obitelji is the recommended choice.

Croatian has no articles, so s obitelji can mean “with (the) family,” often understood as the speaker’s own family from context. To be explicit:

• “with my family” = s mojom obitelji
• “with his/her family” = s njegovom / s njezinom obitelji
• “with the Novak family” = s obitelji Novak

Yes. Croatian often uses the present for scheduled or planned events:

• U ponedjeljak imamo ručak s obitelji.

You can also use the future:

• U ponedjeljak ćemo imati ručak s obitelji.
• Imat ćemo ručak u ponedjeljak. Both are perfectly natural; the present is a bit crisper.

• ponedjeljak: po-ne-DYE-lyak (j = y in “you”; lj like “lli” in “million”)
• imamo: EE-mah-moh (each vowel is clear)
• ručak: ROO-chahk (č = “ch” in “church”)
• s obitelji: s oh-BYE-te-lyee (i is “ee”; lj as above)

Croatian is very phonetic: spellings closely match sounds.

Croatian has no articles. Imamo ručak can be “we have lunch/a lunch/the lunch,” depending on context. If you need to specify, use determiners/adjectives:

• taj ručak = that/that specific lunch
• s cijelom obitelji = with the whole family

Yes—spelling and pronunciation differ by standard variety:

• Croatian: ponedjeljak (ije/je reflex; with dj
  • lj)
• Serbian (Ekavian): ponedeljak Both mean “Monday,” but use the form that matches the standard you’re learning.