Dedication: 3/15/05

opus (gen. operis): work; opera: services

chef d’ oeuvre, co-op, cooperancy, cooperant, cooperate, cooperation, cooperative, cooperatively, cooperator, deoperculate, enure, hand-operated, hors d' oeuvres, inoperable, inoperative, interoffice, interoperable, inure, inurement, magnum opus, maneuver, maneuverable, manure, manurial, modus operandi (m.o.), noncooperation, noncooperative, oeuvre (Fr), office, officeholder, officer, officerless, officership, official, officialdom, officialese, officialism, officiality, officialize, officially, officiant, officiary, officiate, officinal, officinally, officious, officiously, officiousness, op, op. cit., opera, operability, operable, opera-glass, operameter, operand, operant, operate, operatee, operatic, operatically, operation, operational, operationalism, operationalist, operationally, operationism, operative, operatively, operativeness, operator, opercle, opercular, operculate, opercule, operculum, opere citato (op. cit), operetta, operon, operose, operoseness, opry, ops, opus, opuscular, opuscule, Opus Dei, outmaneuver, oval office, patent office, peroperative, petty officer, police office, police officer, postoffice, postoperative, power-operated, preoperation, preoperative, printing office, pseudo-operation, psyop, public office, radio-operator, semi-official, sham operation, soap opera, staff office, uncooperative, uncooperatively, underofficer, underofficial, unofficial, unofficially, victualling-office, watch-officer

Italicized: OED assigns prefix ob-; W3. LS, and ODEE use opus as prefix; OLD ops.