"Most childing" is a rarely used archaic term that means "most childish" or "most immature." The spelling of this word can be explained using IPA phonetic transcription. The "m" is pronounced as /m/, the "o" as /oʊ/, the "s" as /s/, the "t" as /t/, the "c" as /tʃ/, the "h" as /h/, the "i" as /ɪ/, the "l" as /l/, the "d" as /d/, the "i" as /ɪ/, the "n" as /n/, and the "g" as /ɡ/.