semidiameter semidiagrammatic • semidiapason · · · Info · Definitions · Characters · · semidiameter · · Text Latin · · Script 12 · · Length Definitions · · · (noun) the apparent radius of a celestial body when viewed as a disc from the earth. · · Noun Definition 1 Characters · · a latin small letter a U+0061 d latin small letter d U+0064 e latin small letter e U+0065 i latin small letter i U+0069 m latin small letter m U+006D r latin small letter r U+0072 s latin small letter s U+0073 t latin small letter t U+0074