Definition of over- prefix from the Oxford Advanced Learner's Dictionary

over-

prefix

ˈəʊvə(r)

ˈoʊvər

(in nouns, verbs, adjectives and adverbs)1 more than usual; too muchoverproductionoverloadover-optimisticoverconfidentoveranxious2 completelyoverjoyed3 upper; outer; extraovercoatovertime4 over; aboveovercastoverhang