KanjiJLPT N1
Prostrated

prostrated, bend down, bow, cover, lay (pipes)

Mnemonic

Butler Alfred spots a dog lying completely flat on the grand hallway floor, belly pressed to the tiles. He approaches cautiously—but the dog is simply prostrated in total submission, waiting for Alfred to forgive it for shredding the curtains. The dog won't rise until pardoned.
Additional thoughts
Picture Alfred standing upright (the person radical) while the dog lies face-down at his feet—butler plus dog equals utter submission, flat on the ground. The vertical human contrasts with the horizontal, flattened animal.
Quick recall
Butler Alfred's dog lies prostrated on the floor, begging forgiveness.

Details

The keyword for 伏 is prostrated. This kanji conveys the idea of lying face down on the ground, bowing deeply, or crouching low in submission or concealment. It carries connotations of humbling oneself before a superior, hiding, or being subdued. The sense extends to anything that is lying flat, hidden from view, or kept in a state of suppression, such as an ambush or a latent force waiting to emerge.
On'yomi
ふく
Kun'yomi
ふ.せる、ふ.す