失 is built from the 丿 (slash / sweep) and 夫 components.
A common word using 失 is 失敗 (しっぱい), meaning “failure, mistake”.
Don't confuse it with 犬, 太, 大, and 天 — 大 + dot = 犬 (dog); dot inside = 太 (thick); line on top = 天 (sky); line through = 夫 (husband); 失 (lose) has a leading slant