behind
Synonym discussion
Sense: preposition/1
For physical position, 'behind' is the normal everyday word. It can simply mean 'at the rear of', but it often also suggests that one thing is partly hidden by another: 'The cat hid behind the curtain.' 'At the back of' is more neutral and often gives a clearer location inside a space, as in 'Our seats were at the back of the hall.' 'In back of' is common in American English speech, but less usual in formal writing. 'Beyond' usually means farther away than something, not covered by it, so 'the hills beyond the lake' is different from 'the bike behind the shed.'
Etymology
'Behind' comes from Old English forms such as 'behindan' and 'bihindan'. These old forms were built from elements meaning 'by' and 'from the back'. The word first described a position at the rear of a person or thing. Later it kept that picture of being at the back, but widened to ideas of being late, not keeping up, or being the hidden cause or support of something. The informal noun sense for the part of the body you sit on also grows from the same basic idea of the rear side.