11.3 As Part Words [XVI.47, 47.e]

Short-form words are used as parts of words as long as they do not result in a misspelling or obscure recognition of the word. Examples:

besidesquickenmustywould'velittler

As parts of words, short-form words must also maintain their original meaning, therefore:

rafter raft(er)[not]raf
mustachemu(st)a(ch)e[not]m(st)a(ch)e
shoulder(sh)(ou)ld(er)[not](sh)d(er)
mustangmu(st)ang[not]m(st)ang
bloodletter (bleeder)bloodlett(er)[not]bloodlr