used in female names
媜 is a rare kanji used primarily in female given names. Its standalone meaning is unclear beyond that naming usage.
媜 combines 女 (woman) with 貞, which likely contributes the sound. The character was probably created for use in female names, but its exact historical development is uncertain.
A woman (女) beside 貞, a component associated with correctness or virtue. Picture a name chosen to wish a girl a life of upright character.
For テイ, imagine a girl named Taylor whose name contains the sound 'tay' (テイ). The woman radical 女 reminds you it's a female name.