"one who seeks his own selfish interest, to the detriment of justice and mercy," 1630s, from self-seeking or else from self- + seeker.
Entries linking to self-seeker
self-seeking n.
"a seeking after one's own benefit (before those of others), undue attention to one's self-interest," 1580s, from self + seeking, verbal noun from seek. As an adjective from 1620s.
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.
seeker n.
c. 1300, secher (late 13c. as a surname), "one who searches, investigator," agent noun from seek. The religious sect of the Seekers is attested from 1645; they professed no set religion but said they went in search of a true ministry.