word forming element indicating "oneself," also "automatic," from Old English use of self (pron.) in compounds, such as selfbana "suicide," selflice "self-love, pride, vanity, egotism," selfwill "free will." Middle English had self-witte "one's own knowledge and intelligence" (early 15c.).
OED counts 13 such compounds in Old English. Middle English Compendium lists four, counting the self-will group as a whole. It re-emerges as a living word-forming element mid-16c., "probably to a great extent by imitation or reminiscence of Greek compounds in (auto-)," and formed a great many words in the pamphlet disputes of the 17c.
mid-15c., enprowment "profitable use, management of something for profit," from Anglo-French emprowement, from emprouwer "turn to profit" (see improve). Meaning "betterment; act of making better, amelioration" is from 1640s. Meaning "production of something better, something better (than something else)" is from 1712. Meaning "buildings, etc. on a piece of property" is from 1773. Related: Improvements.
<a href="https://www.etymonline.com/word/self-improvement">Etymology of self-improvement by etymonline</a>
Harper, D. (n.d.). Etymology of self-improvement. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/self-improvement