This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 冭 is uncertain. It visually combines 大 (big) and 冫 (ice), but the original meaning and component relationship are unclear.
No clear meaning is available, so a mnemonic based on shape alone is risky. If needed, picture a big (大) block of ice (冫) as a placeholder image.
For タイ, imagine tying a big ice block with a rope: tie -> タイ, while the big 大 sits over the ice 冫.