rule of thumb rule of morphology • rule out · · · Info · Definitions · Synonyms · Characters · · rule of thumb · · Text Common · · Latin · · Scripts 13 · · Length 4 · · Syllables Definitions · · · (noun) a rule or principle that provides guidance to appropriate behavior. Synonyms: guidepost, guideline, rule of thumb. · · Noun Definition 1 Synonyms · · · guidepost · · Synonym 1 guideline · · Synonym 2 Characters · · space U+0020 b latin small letter b U+0062 e latin small letter e U+0065 f latin small letter f U+0066 h latin small letter h U+0068 l latin small letter l U+006C m latin small letter m U+006D o latin small letter o U+006F r latin small letter r U+0072 t latin small letter t U+0074 u latin small letter u U+0075