[noun](phonology,orthography,grammar) the fifth and lowest-graded column of the 五十音図(literally “table of the fifty sounds”), consisting of the ten kana お/オ(o), こ/コ(ko), そ/ソ(so), と/ト(to), の/ノ(no), ほ/ホ(ho), も/モ(mo), よ/ヨ(yo), ろ/ロ(ro) and を/ヲ(wo)
Alternative spelling オ段
(This term, 於段, is an alternative spelling of the above term.)