decline, slide
頽 centers on a downward loss of strength or position: declining, sliding, or collapsing from a former state.
頽 is a phono-semantic compound: 秃 (bald, bare) suggests the sound タイ, while 頁 (head) relates to the head or top, together conveying the idea of the top becoming bare or declining. The exact historical development is uncertain.
The left side 秃 looks like a bare, bald slope, and the right side 頁 is a head. Imagine a head sliding down a bare hill as strength declines.
For タイ, picture a tie slipping off a bald head: tie -> タイ, and the slide of the tie mirrors the kanji's meaning of decline.