簡単【かんたん】
simple, easy, uncomplicated, brief, quick, light
単純【たんじゅん】
simple, plain, uncomplicated, straightforward, simple-minded, naive
単なる【たんなる】
mere, simple, sheer
単位【たんい】
unit, denomination, credit (in school), in units of (e.g. "in thousands"), in amounts of
単に【たんに】
simply, merely, only, solely
単語【たんご】
word, vocabulary
単独【たんどく】
sole, single, solo, independence, singleness, singularity
単一【たんいつ】
single, simple, sole, individual, unitary
単行本【たんこうぼん】
standalone book (i.e. not part of an anthology, series, etc.), (book published as a) single volume, tankōbon, individual volume of a manga series
単調【たんちょう】
monotony, monotone, dullness, monotone, monotonic
単身【たんしん】
alone, unaided, away from home
単価【たんか】
unit price, unit cost
単産【たんさん】
(single-industry) industrial union
単発【たんぱつ】
firing one shot at a time, single-shot gun, having only one engine, single-engined aeroplane, single-engined airplane, one-shot (e.g. story), non-serial, one-off, single occasion
単勝【たんしょう】
winning at the races
単純化【たんじゅんか】
simplification
単線【たんせん】
single track (railway), single line, solid wire, solid-core wire, single-strand wire
単純平均【たんじゅんへいきん】
simple average, arithmetic average
単体【たんたい】
simple substance (e.g. chemical), something standing alone, separate item, solo item
単色【たんしょく】
single colour (color), monochrome