アラビア数字[arabiasuuji] Arabic numeral
キリル文字[kirirumoji] Cyrillic character
ギリシア文字[girishiamoji] Greek character
羅馬字[roomaji] Latin alphabet
ロシア文字[roshiamoji] Russian character

異体字[itaiji] kanji variants
一字[ichiji] letter
一字千金[ichijisenkin] word of great value
一丁字[itteiji] single letter or character
一文字[ichimonji] straight line

悪習[akushuu] bad habit
悪習慣[akushuukan] bad habit
演習[enshuu] practice
演習問題[enshuumondai] practice problem
演奏練習[ensourenshuu] musical rehearsal

学習[gakushuu] study
学習者[gakushuusha] learner
学習塾[gakushuujuku] private night-school
学習用[gakushuuyou] tutorial
学習用ヘルプ[gakushuuyouherupu] tutorial help