also: いちくみ
noun
one class (of students); one group (of people); one set (of items); one pair
Used to count one unit of a group, class, set, or pair. The reading ひとくみ is standard; いちくみ is rare.
この学校には一組から三組までのクラスがあります。
This school has classes from group 1 to group 3.
一組の茶碗を買いました。
I bought one set of teacups.
Compound of 一 (ひと, 'one') and 組 (くみ, 'group, set, class'). The reading ひとくみ follows the native Japanese counting system.