KanjiJLPT N4
Loss

lose, error, fault, disadvantage, loss

Mnemonic

A comet hurtles toward Earth and slams into the home of a devoted husband. He survives, but every photograph, heirloom, and letter from his late wife is vaporized instantly. Standing at the edge of the smoking crater, he feels a loss so deep nothing could ever fill it.
Additional thoughts
Picture the comet's tail sweeping downward like the first stroke of 失, while the husband's sturdy stance forms the lower crossing strokes. The cosmic scale of destruction reinforces the totality of loss.
Quick recall
A comet obliterates a husband's every treasure, leaving him with nothing but loss.

Details

The keyword for 失 is loss. This kanji conveys the idea of losing something, whether it be a physical object, an opportunity, or an abstract quality. It encompasses meanings such as failure, mistake, or the act of letting something slip away. It is often associated with the unintentional forfeiting of something one previously possessed.
On'yomi
しつ
Kun'yomi
うしな.う、う.せる