• 失敗しっぱい — failure; mistake
• 失礼しつれい — rudeness; “excuse me”
• 損失そんしつ — loss; damage
• 喪失そうしつ — loss (of something abstract)
• 消失しょうしつ — disappearance; loss
• 失望しつぼう — disappointment
• 失業しつぎょう — unemployment

The character 失 likely derives from a hand letting something slip — symbolizing loss. It commonly appears in words about failure, error, or losing something material or abstract (opportunity, manners, employment).

チャンスを失うしないました。
I missed the opportunity.

失敗しっぱいは 成功せいこうのもと。
Failure is the mother of success.

失礼しつれいします。
Excuse me. / Pardon me.