いったん悪い癖がつくと、なおすのは難しい。

once; for a moment; temporarily; one morning

bad; poor; inferior; evil; sinful; unprofitable; unbeneficial; at fault; to blame; in the wrong; sorry

habit (often a bad habit, i.e. vice); tendency; peculiarity; idiosyncrasy; mannerism; crease; wrinkle; curl; kink

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

to be attached; to be connected with; to adhere; to stick; to cling; to remain imprinted; to scar; to stain; to dye; to bear (fruit, interest, etc.); to be acquired (of a habit, ability, etc.); to increase (of strength, etc.); to take root; to accompany; to attend; to follow; to study with; to side with; to belong to; to possess; to haunt; to be lit; to be lighted; to be settled; to be resolved; to be decided; to be given (of a name, price, etc.); to be sensed; to be perceived; to be lucky; to become (a state, condition, etc.)

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)

to cure; to heal; to fix; to correct; to repair; to do over again (after -masu base of verb); to replace; to put back as it was; to convert (into a different state); to transform

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

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

difficult; hard; troublesome; complicated; serious (disease, problem, etc.); fussy; particular; fastidious; hard to please; displeased; gloomy; glum; sullen; serious (look); dirty; unclean; filthy; detestable; unpleasant; uncomfortable; creepy; spooky