straighten / straiten are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
straighten: (verb) straighten up or out; make straight. (verb) make straight. (verb) get up from a sitting or slouching position. (verb) make straight or straighter.
straiten: (verb) bring into difficulties or distress, especially financial hardship. (verb) squeeze together.
straighten: s·t·r·EY·t·ah·n
straiten: NA
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)