"appointed or nominated by oneself," 1750, from self- + appointed.
Entries linking to self-appointed
self-
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.
appointed adj.
with qualifying adverb, "equipped, furnished," 1530s, from past participle of appoint (v.) in the specialized sense of "equip, furnish" (late 15c.).