Every language has many idiomatic phrases, constructs that have unexpected meanings. Generally they cannot be translated from language to language.
The following words have often-seen abbreviations, which do not change through cases and singular/plural. Abbreviations having more than one letter end with a period (.), and one-letter abbreviations do not:
word abbr. meaning godina god. "year" komad kom. "piece" minuta min. "minute" mjësec mj. "month" sat h (!) "hour"
word abbr. meaning sekunda sek. "second" stoljëće st. "century" stranica str. "page" sveti, sveta sv. adj. "saint" ulica ul. "street"
Therefore, while in English you would see "1 pc" ("piece"), "2 pcs" ("pieces"), in Croatian it's always 1 kom. (1 komad), 2 kom. (2 komada) etc.
Many abbreviations common to the metric system are also often seen, such as m (metar), kg (kilogram), etc.
A few often used phrases have standard abbreviations:
phrase abbr. meaning (Engl. abbr.) na primjër npr. "for example" (e.g.) to jest tj. "that is" (i.e.) i tako dalje itd. "et cetera" (etc.) takozvani adj. tzv. "so-called"
I have included tzv. here, it could be included in the previous table as well.
Furthermore there are some phrases where words are always used together but meaning can be easily deduced:
phrase literal meaning postavim pitanje "pose a question" "ask a question" položim ispit "lay down an exam" "pass an exam" prëma tome "according to that" "therefore" u ime + gen. "in the name of" "on behalf of"
There are some phrases involving 'modal' na + acc., that translate to English adverbs:
phrase literal meaning na brzinu "on speed" "hastily" na sreću "on luck" "luckily, fortunately" na vrijëme "on time" (same as the English phrase) na žalost "on regret" "unfortunately, regrettably"
They are sometimes spelled as one word (e.g. nažalost).
Some other phrases having completely shifted meanings are:
Bogu iza leđa "middle of nowhere"
grom iz vedra neba "out of the blue"
imam i ovce i novce "have cake and eat it"
nalazim (~ nađem) zajednički jezik "find a common ground"
mačji kašälj "nothing serious"
na licu mjësta "on the spot, immediately"
ni pet ni šest "without hesitation"
ostavljam (~ ostavim) na cjëdilu "leave out in the cold", "betray"
ostavljam (~ ostavim) na miru "leave alone"
pao s Marsa "without a clue", "without any prior knowledge"
prëpušten sam sebi "left to his/her own devices"
punom parom "full steam"
spajam (~ spojim) kraj s krajem "make ends meet"
špansko selo "something completely unknown"
u (punom) jeku "in full swing"
trn u oku or trn u peti "thorn in one's side"
živim na visokoj nozi "spend lavishly, have extravagant lifestyle"
This is just a short list, there are many other phrases.
Euphemisms are words or phrases that are used instead of something we cannot say openly for some reason. For instance a verb preminem "pass away" is used instead of umrem, umro, umrla, umrijëti "die". Also, when someone dies, reasons are seldom said clearly, a phrase nakon kratke/duge i teške bolesti "after a short/long and serious illness" is used instead.
It's worth noting that Standard Croatian has different verbs used with meaning "die" depending on who dies. For people, umrem, umro, umrla, umrijëti (or preminem), but for animals crknem should be used instead. However, many speakers use just umrem in all occasions.
Note that Croatian has relatively few Bible-based phrases, despite Croats being traditionally Catholics.
Updated 2014-08-22 (v. 0.4)