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.), overshort, etc.
mid-14c., "furnish with" (goods, provisions, etc.), also "reinforce" (troops), from Old French estofer "pad, upholster, fit out" (Modern French étoffer), from estoffe, and probably also in part from stuff (n.).
From c. 1400 as "fill, cram full; fill (the belly) with food or drink, gorge;" from early 15c. as "to clog" (the sinuses, etc.); from late 14c. as "fill (a mattress, etc.) with padding, line with padding;" also in the cookery sense, in reference to filing the interior of a pastry or the cavity of a fowl or beast. The ballot-box sense is attested from 1854, American English; in expressions of contempt and suggestive of bodily orifices, it dates from 1952.