Adjustable means able to be altered to suit the person using it. Chairs, straps, spanners and mortgages.
It is a selling point on almost anything worn or sat in, since an adjustable strap fits more people and an adjustable chair prevents a great deal of back trouble. Tools use it precisely, and an adjustable spanner has a jaw that widens. Finance has adjustable rates, which move with the market and are called variable in Britain. The verb is adjust and the noun is adjustment.
1adjectiveadjustableAble to be altered to suit different needs or sizes.
“The straps are fully adjustable.”
Vulgar Latin
*adiuxtāre
Old French
ajouster
Latin
ad — to, up to, towards
Middle French
adjuster
Middle English
ajusten
English
adjust
English, today
adjustable
Built from
From adjust + -able. adjust comes from Middle English ajusten, borrowed from Middle French adjuster, or Old French -, from Latin ad (“to, up to, towards”) + iustus (“correct, proper, exact”); Equivalent to ad + just. Probably influenced in sense by Old French ajouster (cf. modern ajouter), from Vulgar Latin adiuxtāre, from Latin iuxta. The Middle English originally meant "to correct, remedy" in the late 14th century, and was reborrowed from Middle French in the early 17th century. According to another view on the etymology, the word was actually derived from Old French ajouster and then supposedly later influenced by folk etymology from Latin iustus; if so, it is a a doublet of adjute.
Etymology from Wiktionary, CC BY-SA