also: け
noun
ruled line; rule
Refers to a printed or drawn line on paper, such as on ruled notebook paper or forms.
ノートの罫に沿って文字を書く。
Write letters along the ruled lines of the notebook.
noun
line on a game board
Specifically the grid lines on a go board, shogi board, or similar game boards.
碁盤の罫の交点に石を置く。
Place a stone on the intersection of the lines of the go board.