Straight Line
noun
When you have one writing letter what do you have? Here's a hint, there's one kanji in this word that consists of one writing letter (aka a straight line).
いちもんじ
This is a jukugo word, which usually means on'yomi readings from the kanji. Since 文 has two on'yomi readings, here's a mnemonic to help you remember which one to use: Straight lines are for monsters (もん). Only a monster would ever draw a perfectly straight line. You're no monster, so no straight lines for you!
女の子は、おこって口を一文字にむすびました。
The girl got angry and her mouth pursed into a straight line.
サーモンに一文字の切り目が入ってます。
The salmon has a straight line cut across it.
たくさんのドローンが一文字になってとんでいる。
Quite a few drones were flying in a straight line.