Other forms: straightened, straightening, straightens
To straighten something is to make it flat, level or tidy when it was bent or crooked. A picture on a wall, a bent nail, a crooked tie.
It works both ways round, since you straighten your back and your back straightens. Hair straighteners are a whole industry. The phrasal forms do a lot of work: straightening up means tidying a room or standing upright, and straightening something out means resolving a confusion or a dispute. It belongs to the -en family beside flatten, widen and sharpen.
1verbstraightenTo make or become straight or level.
“She straightened the picture above the fire.”
2verbresolveTo resolve a confusion or difficulty.
“They straightened out the misunderstanding over lunch.”
Proto-West Germanic
*strakkjan — to stretch
Old English
streċċan
Middle English
streight
English
straight
English, today
straighten
Built from
From straight + en. Compare Scots strauchten (“to straighten”). straight comes from Middle English streight, streght, streiȝt, the past participle of strecchen (“to stretch”), from Old English streċċan (past participle ġestreaht, ġestreht), from Proto-West Germanic strakkjan (“to stretch”). Cognate with Scots straicht (“straight”), Dutch gestrekt (“stretched”), German gestreckt (“stretched”), Danish strakt (“stretched”), Faroese - and nrn strekti (“stretched”), Icelandic strekkti (“stretched”), Norwegian strekte (“stretched”), Swedish sträckte (“stretched”). Doublet of straught. Equivalent to stretch + ed. In some senses, conflated with strait (“narrow, constricted”), which is from Latin strictus via Old French estreit.
Etymology from Wiktionary, CC BY-SA