popular  usually written using kana alone  adverb 

• at once, immediately, instantly, in an instant, quickly, suddenly, on the spur of the moment

popular  rarely used kanji form  usually written using kana alone  adverb 

• (not) well, (not) properly, (not) enough, (not) sufficiently, (not) satisfactorily, (not) decently

popular  JLPT N1  noun  noun (generic)  adverb 

• one day
• all day (long), the whole day, from morning till night
• 1st day of the month

popular  gikun or jukujikun  JLPT N5  usually written using kana alone  adverb 

• why, how, for what reason

popular  JLPT N3  usually written using kana alone  adverb 

• always, all the time, at all times
• (at) any time, whenever (you like)

popular  JLPT N1  noun  noun (generic)  dated term  adverb 

• truth, reality, fact
• sincerity, honesty, faithfulness, good faith
• indeed, really, absolutely, truly, actually, very, quite

popular  irregular okurigana  JLPT N5  usually written using kana alone  な adjective  adjective (generic)  adverb  noun  noun (generic) 

• straight (ahead), direct, upright, erect
• straightforward, honest, frank

popular  noun  noun (generic)  adverb 

• recently, the other day

popular  noun taking the genitive case particle の  adjective (generic)  な adjective  noun  noun (generic)  adverb  dated term 

• direct
• honest, frank, straightforward, candid
• easygoing, lighthearted, friendly
• night duty, night watch
• being on duty (in a factory), shift

popular  JLPT N3  adverb  noun  noun (generic) 

• here and there, this way and that way, everywhere, all over