Closed-up style is avoided in some cases: possible homographs, such as "recreation" (fun or sport) versus ' (the act of creating again), "retreat" (turn back) versus ' (give therapy again), and ' (not in ion form) versus "unionized" (organized into trade unions); combinations with proper nouns or adjectives (', '); acronyms (', '); or numbers (', '). Although ' is still hyphenated by both "Dorland's" and "Merriam-Webster's Medical"), the solid (that is, unhyphenated) styling ("protooncogene") is a common variant, particularly among oncologists and geneticists.