also: きそれん · キソレン
noun
basic training; practicing the basics
Slang abbreviation of 基礎練習 (kiso renshū). Used mainly in sports, music, or skill-based activities to refer to fundamental drills or practice.
今日の部活は基礎レンだけだった。
Today's club practice was just basic drills.
基礎レンをしっかりやらないと上達しないよ。
You won't improve if you don't do your basic training properly.
The full, formal term for basic practice or fundamental training. 基礎レン is the casual, abbreviated slang form used in conversation.
Abbreviation of 基礎練習 (kiso renshū, 'basic practice'), formed by taking the first two kanji 基礎 and the first katakana レン from 練習.