osteostracan osteostomous • Osteostraci · · · Info · Definitions · Synonyms · Characters · · osteostracan · · Text Latin · · Script 12 · · Length Definitions · · · (noun) extinct jawless fish of the Devonian with armored head. Synonyms: cephalaspid. · · Noun Definition 1 Synonyms · · · cephalaspid · · Synonym 1 Characters · · a latin small letter a U+0061 c latin small letter c U+0063 e latin small letter e U+0065 n latin small letter n U+006E o latin small letter o U+006F r latin small letter r U+0072 s latin small letter s U+0073 t latin small letter t U+0074