The language group prominently spoken in Trek media is that of Gol-Vuhlkansu (GV), or Golic Vulcan. Modern Golic Vulcan (MGV) is, for example, Spock's first language. It is descended from Ancient Golic Vulcan (AGV), although it also has influences and loanwords from other languages. AGV remains in ceremonial usage - for example, it is likely what was spoken by T'Pau at Spock's koon-ut-kal-if-fee in Amok Time and T'Lar in The Search for Spock.
The Vulcan Language Institute (VLI) was very influential in the development of Vuhlkansu as a conlang/group of closely related conlangs. Among other things which will likely later be discussed, including extensive vocabulary and grammatical work, they (possibly originated? but certainly-) developed Gol-Vuhlkansu being one of several Vulcan languages, and the one mostly spoken onscreen.
As far as I am aware, the VLI is now defunct; their website is no longer maintained. They have a Facebook page which was last active in 2022 to note the death of Saavik actress Kirstie Alley.
In Wrath of Khan, when Spock shifts from addressing Saavik by rank to addressing her as “Saavikam” (an affectionate diminutive), his enunciation becomes almost exaggerated. I think this makes perfect sense, & I think that the Vulcan equivalent of voice going high when you talk to a cute kid is instead over-enunciating to better aid their language development with minimum confusion —hence the TOS episode where Spock is completely baffled by baby talk and ordered to drop the line of inquiry and consult linguistics later.
Names and pronouns are rarely used in Vulcan languages unless they are absolutely necessary for comprehension (or, in the case of some names and nicknames, used to indicate affiliation). When talking about somebody, 'ik-banu,' 'that one,' is often favoured over the person's name. When talking about oneself, 'nash-veh,' 'this one,' is often used as a first-person pronoun. GV does not have gendered pronouns.
This word, as do its nuances, comes from the novel Spock’s World. It is commonly translated as 'lack of emotion' or 'suppression of emotion,' but a more accurate translation is 'passion's mastery.' The word acknowledges that Vulcans have emotions, but manage them rather than being managed by them.
This word, as do its nuances, also comes from the novel Spock’s World. It is usually translated as ‘logic,’ but this is not wholly accurate. A closer translation would be ‘reality-truth.’
"It’s the modern Vulcan word which we translate as ‘logic.’ But what it more correctly means is ‘reality-truth.’ The truth about the universe, the way things really are, rather than the way we would like them to be. It embraces the physical and the inner realities both at once, in all their changes. The concept says that if we do not tell the universe the truth about itself, if we don’t treat it and the people in it as what they are—real, and precious—it will turn against us, and none of our affairs will prosper. That’s a child’s explanation of the word. I’m afraid. Whole books have been written attempting to define it completely. What Sarek is saying is that if we don’t handle this matter with the utmost respect for the truth, for what is really needed by everyone involved, it will end in disaster."
Please note that these are extremely clumsy and uncertain! I’m a novice, not a linguist.
Line from the novel The IDIC Epidemic (spoken by Spock, to Sarek):
English/Fed.Stand.Ang: “Logic? To send a Vulcan into a flood? Can you swim, father?”
Gol-Vuhlkansu: “Cthia? Satau Vuhlkansu vi’abrash? Mahal-tor kup du, Sa-mekh?”
Literal English translation: “Reality-truth? Send Vulcan into flood? Swim can you, father?”
Just for fun:
English/Fed.Stand.Ang: Go, my psionic warriors!
Gol-Vuhlkansu: Haltor, ahkhinahru!
Literal English translation: Go, psionic-warriors!
English/Fed.Stand.Ang: Never gonna give you up, never gonna let you down…
Gol-Vuhlkansu: Dungi-tan-tor worla kwi’su, dungi-vravshau kwi’su…
Literal English translation: Will-give far-away you-never, will-fail you-never…
The Vuhlkansu dialogue in Wrath of Khan was originally spoken in English, then James Doohan (who played Scotty) came up with words that could also fit the mouth movements, and the actors dubbed the dialogue over.
Official subtitles: He’s never what I expect, sir.
Vuhlkansu: Gishen worla ik-banu.
My literal translation: As expected never that person.
My rendition: He’s never what I expect.
If she'd actually said 'sir,' you could have expected an 'osu' in the sentence somewhere, either on its own or in the form of an 'o-' honorific.
Official subtitles: What surprises you, lieutenant?
Vuhlkansu: Wakli ak’wikman, otlan?
My literal translation: How surprise officer?
My rendition: How were you surprised, lieutenant?
Official subtitles: He’s so -- human.
Vuhlkansu: Ish-veh, ni kohmin.
My literal translation: That one so human.
My rendition: He is so -- human.
Official subtitles: Nobody’s perfect, Saavik.
Vuhlkansu: Kling akhlami buhfik, Saavikam.
My literal translation: Nobody among us perfect, my little Saavik.
My rendition: None of us are perfect, Saavikam.