| oa | oak (69), oasis (57), oat (14) |
| ob | objective (453), object (254), obligation (163), obstacle (107), observation (66), observatory (19), obstetric (18), obesity (16), obuda (8) |
| oc | october (568), occasion (288), ocean (125), occupational (68), occupation (48), occupancy (36), occaecati (15), occurrence (13) |
| od | odio (277), odor (14) |
| oe | oeuvre (21) |
| of | office (2096), offer (1714), official (628), officer (179), officia (90), officially (89), offering (57), offset (27), offence (16) |
| oi | oil (435), oily (16) |
| ok | okay (32) |
| ol | olive (59), olympic (39), olson (12), olympiad (6) |
| on | ongoing (186), onion (79), oncology (22) |
| op | open (2479), opportunity (1445), operation (1335), option (986), opinion (372), optimal (292), operational (267), optimization (265), operator (261), operate (215), optional (125), optical (98), opposite (73) 11 more keywords » |
| or | order (2024), organization (893), original (596), organisation (424), organic (276), orci (255), origin (211), organizational (182), organizer (175), ornare (157), oral (150), orange (133), orientation (103) 14 more keywords » |
| ou | outstanding (613), outdoor (561), outside (486), outcome (124), output (110), outer (66), outpatient (30), outline (27), outsource (22) |
| ov | overall (255), overview (190), oven (136), overseas (50), overhead (36), overnight (32), overlay (31), oversized (29), overweight (21), overdue (16) |
| ow | owner (940), ownership (193), owl (18) |
| ox | oxide (26), oxidation (10) |