late 14c., "to clothe in the official robes of an office," from L. investire
"to clothe in, cover, surround," from in
"in, into" + vestire
"to dress, clothe" (see wear
). The meaning "use money to produce profit" first attested 1610s in connection with the East Indies trade, and is probably a borrowing of It. investire
(13c.) from the same L. root, via the notion of giving one's capital a new form. The military meaning "to besiege" is from c.1600.