亜あ門もんあもんMeanings1nounsubphylum; subdivisionbiologyA taxonomic rank in biology below phylum and above class; used in scientific classification.脊せき椎つい動どう物ぶつは脊せき索さく動どう物ぶつ門もんの亜あ門もんに分ぶん類るいされる。Vertebrates are classified into a subphylum of the phylum Chordata.