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."
1630s, "to make larger, increase," from French agrandiss-, present participle stem of agrandir "to augment, enlarge" (16c.), ultimately from Latin ad "to" (see ad-) + grandire "to make great," from grandis "big, great; full, abundant" (see grand (adj.)). The double -g- spelling in English (also formerly in French) is by analogy with Latin words in ad-. Related: Aggrandized; aggrandizing.
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<a href="https://www.etymonline.com/word/self-aggrandizing">Etymology of self-aggrandizing by etymonline</a>
Harper, D. (n.d.). Etymology of self-aggrandizing. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/self-aggrandizing