overjoy v.

word-forming element meaning variously "above; highest; across; higher in power or authority; too much; above normal; outer; beyond in time, too long," from Old English ofer (from PIE root *uper "over"). Over and its Germanic relations were widely used as prefixes, and sometimes could be used with negative force. This is rare in Modern English, but compare Gothic ufarmunnon "to forget," ufar-swaran "to swear falsely;" Old English ofercræft "fraud."

In some of its uses, moreover, over is a movable element, which can be prefixed at will to almost any verb or adjective of suitable sense, as freely as an adjective can be placed before a substantive or an adverb before an adjective. [OED]

Among the old words not now existing are Old English oferlufu (Middle English oferlufe), literally "over-love," hence "excessive or immoderate love." Over- in Middle English also could carry a sense of "too little, below normal," as in over-lyght "of too little weight" (c. 1400), overlitel "too small" (mid-14c.), oversmall (mid-13c.), overshort, etc.

c. 1200, "feeling of pleasure and delight;" c. 1300, "source of pleasure or happiness," from Old French joie "pleasure, delight, erotic pleasure, bliss, joyfulness" (11c.), from Latin gaudia "expressions of pleasure; sensual delight," plural of gaudium "joy, inward joy, gladness, delight; source of pleasure or delight," from gaudere "rejoice," from PIE root *gau- "to rejoice" (cognates: Greek gaio "I rejoice," Middle Irish guaire "noble").

As a term of endearment from 1580s. Joy-riding is American English, 1908; joy-ride (n.) is from 1909.