Learn Hardcore Turkish: Yarın randevulaşalım; saat iki uygun mu? - Let’s set an appointment tomorrow; is two o’clock okay?

It’s the first-person plural optative/volitional: “let’s …”. Since randevulaşmak means “to make an appointment with each other,” randevulaşalım means “let’s arrange an appointment.”

How is randevulaşalım formed? Why not randevulaşelim?

Breakdown: randevu (appointment) + -laş- (reciprocal/“do with each other”) + -a- (optative theme vowel) + -lım (1st person plural). Vowel harmony decides the vowels:

From randevu, the suffix is -laş- (not -leş-) because the last vowel is back (u).
Before -lım, the last vowel in the stem is now a, so you get -alım, not -elim.

Why is mu separate in uygun mu?

Because mi/mı/mu/mü is the question particle. It’s written as a separate word, and it obeys vowel harmony with the last vowel of the preceding word. With uygun (last vowel u), you use mu: uygun mu. If you add further suffixes, they attach to the particle: uygun mudur?

Where do I place the question particle? What’s the difference between “saat iki uygun mu?” and “saat iki mi uygun?”

Saat iki uygun mu? = Is two o’clock suitable? (neutral yes/no about suitability)
Saat iki mi uygun? = Is it two o’clock that’s suitable? (contrastive focus on “two” vs some other time)

What’s the difference between saat iki and iki saat?

saat iki = two o’clock (a clock time)
iki saat = two hours (a duration) They are not interchangeable.

Can I say Saat ikide uygun musun? What changes?

Yes. Saat ikide uygun musun? means “Are you available at two o’clock?” It addresses the other person directly (2nd person singular, with musun), and uses the locative -de: iki + -de → ikide.
By contrast, Saat iki uygun mu? is impersonal: “Is two o’clock suitable?” (for you/us), leaving the person implicit.

Do I need için after yarın?

No. Yarın randevulaşalım is fine. If you want to be extra explicit about the time reference, you can say Yarın için saat iki uygun mu? (“Is 2 o’clock okay for tomorrow?”).
Avoid writing yarında unless you mean “tomorrow too,” which would be yarın da (with the clitic separate).

Is the semicolon necessary here?

No. It’s just stylistic. You could use a period or a comma instead:

Yarın randevulaşalım. Saat iki uygun mu?
Yarın randevulaşalım, saat iki uygun mu? A dash also works. One question mark at the end is enough, since only the second clause is a question.

How is randevulaşmak different from buluşmak, görüşmek, randevu almak, and randevu ayarlamak/yapmak?

randevulaşmak: to arrange an appointment with each other (mutual scheduling).
buluşmak: to meet up (actually meet).
görüşmek: to meet/talk/discuss (in person or by phone/online).
randevu almak: to get an appointment (usually from a third party like a clinic).
randevu ayarlamak/yapmak: to arrange/make an appointment (general/neutral). Your sentence suggests “let’s arrange one together.”

How can I soften “Is two o’clock okay?” for politeness?

Common options:

Saat iki uygun olur mu? (Would two be okay?)
Saat iki olur mu? (Would two work?)
Saat iki uyar mı? (Does two suit you?)
Saat iki uygun mudur? (more formal)

Any pronunciation tips for yarın, randevulaşalım, and mu?

yarın: the dotless ı is a close back unrounded vowel (like a relaxed “uh”); roughly “YA-rın.”
randevulaşalım: syllables ra–nde–vu–la–şa–lım; ş = “sh”; main stress is typically final: randevulaşaLIM.
mu: pronounced “moo,” usually unstressed; the stress falls on the word before it: uyGUN mu.

Why is there no explicit “we” (biz)?

Turkish verbs encode person/number. The ending -lım already means “we,” so biz is optional and used only for emphasis: Biz yarın randevulaşalım.

How can I make the suggestion more tentative, like “Shall we…?”

Use a question or a conditional:

Yarın randevulaşalım mı? (Shall we make an appointment tomorrow?)
Yarın randevulaşsak mı? (What if we made an appointment tomorrow?) — softer/hedged.