悪さ|わるさwarusa[1]atamadaka (head-high)

1. nounbadness; mean mischief
   親おやがいないとどうしようもないほど悪わるさをする子供こどもたちもいるものだ。↗

   Some children are as bad as they can be while their parents are gone.

• Related悪あくNeutralA single-character written word for evil or sin; also the villain in a play. 「悪さ」 leans toward mischief or the degree of badness.
• Related不良ふりょうNeutralCovers poor quality or defective goods and delinquent youths; 「悪さ」 is about pranks, mischief, or how bad something is.
• Related邪よこしまWrittenWritten/formal prose for a crooked or wicked mind, as in 「邪な心」; 「悪さ」 is about mischief or the degree of badness.
• Related邪悪じゃあくWrittenWritten/formal for wickedness in a person's heart or a being's nature; 「悪さ」 usually means doing bad things, pranks, or how bad something is.
• Antonym良さよさNeutralThe opposite: merit, good points, or the degree to which something is good, standing against 「悪さ」 as a degree of badness.

Use 「悪さ」 for doing bad things, pranks, or the degree of badness, as in 「悪さをする」 and 「頭の悪さ」. For evil or sin in written prose pick 「悪」, for wickedness 「邪悪」; the opposite is 「良さ」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 悪わるいことやその程度ていど。
2. 悪戯いたずら。