So here's a guide for the perplexed. In the comments, please add any monosyllables I missed!
"Nu" is basically a verbal nudge-- best translation into English might be "come on!" or "well?" As my husband says, it means "well?" in both the "how are you?" and the "what's your excuse for living" contexts. Gains extra power when combined with "cvar," which means "already." Expresses impatience.
- Example: Nu cvar, are you going to call Dudu about the falofel?
"Um" in Hebrew is "Eh." They might not tell you that in Hebrew/English dictionaries, but I've found that a key to sounding like a foreigner is to fill your pauses with their version of "um"... In France, for example, say "euh" and you'll stop getting snooty looks.
- Example: Dudu said... ehhhh... the falofel will be ready after he makes delivery to... ehhhh.... Caesarea.
Yo! (Alternative: "yoo")
This monosyllable is not actually the same as "yo" in the US. This isn't a greeting or an attention-getter. Rather, "yo" in Hebrew is what frechot (valley girls, basically) use to express shock or surprise. Kind of like the Israeli "Oh my gosh!" or "No way!" I learned this phrase from watching the Israeli version of "Beauty and the Geek"-- the beauties used "yo" as every other word.
- Example: Yo, 20 shekels for falofel? Is Dudu crazy?
Ooo-wah (alternative: "eh-oh")
Ok, so this is really bi-syllabic. But you say "ooo-wah" when somebody does something surprising or extreme, like state a ridiculous price in the shuk or threaten a person carrying an Uzi. In contrast to "yo," which just expresses surprise, "ooo-wah" conveys gentle censure of the person engaging in the extreme action.
- Example: Ooo-wah! You're calling Dudu crazy? You know he carries an Uzi, no?
Hmm, this one is hard for me to define. "Ooof" is the sound you make when something lands heavily on your stomach, so it's also the sound you make when something lands heavily in your lap in a metaphorical sense.
- Example: Ooof, all these people complaining about the falofel.
While this one is mostly used by the elder generation, "oy" is alive and well as a complaint on Israeli streets. Gains extra power when combined with "gevalt," "vey," or "kashe kashe kashe" (hard hard hard).
- Example: Oy, when will these young folks stop complaining? When I was in the Russian army...
Closely related to "oy," this is the Israeli "ouch." When something really hurts (either in a literal or figurative sense), can be extended to "aiyaiyai."
- Example: Aie, Dudu! You just ran over my foot with your delivery scooter!
Oh-pah (Alternative: ooh-pah) **Update: BJ observes in the comments that "oh-pah" is probably borrowed from the Greeks... which fits perfectly with how it's used.**
This is the Israeli "oops"... or "be careful," usually spoken after the fact. You might say "oh-pah" to the woman who trips in front of you, spilling all her groceries on the ground. (Then, being Israeli, you would help her pick everything up while explaining in detail how she was carrying the groceries all wrong.)
- Example: Oh-pah! Next time, don't walk out in front of Dudu's scooter!
This is really a word, so it's actually in the dictionary and will show up in Hebrew courses (and seder texts as "dayeinu"). However, this word-- which means "enough"-- definitely deserves a spot on this list, if nothing else for the way it garners Israeli parents dirty looks when they shout it at their children in American supermarkets.
- Example: Nu, die cvar! Stop asking me about Dudu and his falofel!