millimetre millimeter of mercury • millimicron · · · Info · Definitions · Synonyms · Characters · · millimetre · · Text Latin · · Script 10 · · Length 3 · · Syllables Definitions · · · (noun) a metric unit of length equal to one thousandth of a meter. Synonyms: millimeter, mm. · · Noun Definition 1 Synonyms · · · millimeter · · Synonym 1 mm · · Synonym 2 Characters · · e latin small letter e U+0065 i latin small letter i U+0069 l latin small letter l U+006C m latin small letter m U+006D r latin small letter r U+0072 t latin small letter t U+0074