beautiful, lazy, languid
媠 centers on a state of relaxed, effortless beauty that can tip into laziness or languidness. The meanings 'beautiful' and 'lazy/languid' are connected by the idea of a graceful, unhurried ease.
The exact historical development of 媠 is uncertain. It combines 女 (woman) with a right-side component that may have contributed sound, but the origin of the combined meaning is not clearly established.
A woman 女 beside a shape that looks like a relaxed figure with a drooping head and a rounded belly. Picture a beautiful woman lounging in a languid, lazy pose.
For タ, imagine a beautiful but lazy person sighing 'taa' as they stretch out languidly: taa -> タ.