列車のコンパートメントはすぐ窮屈になる。

train (ordinary)

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

compartment

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

immediately; at once; directly; soon; before long; shortly; easily; without difficulty; right (near); nearby; just (handy)

narrow; tight; cramped; formal; stiff; strict; ceremonious; rigid; constrained; uncomfortable; tight (e.g. finances)

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

to become; to get; to grow; to be; to reach; to attain; to result in; to prove to be; to consist of; to be composed of; to succeed; to be complete; to change into; to be exchanged for; to play a role; to be promoted; to do ...