blackened eyebrows
黛 centers on the cosmetic practice of blackening eyebrows, typically with a dark pigment. The meaning is specific to this traditional makeup technique.
黛 combines 代 (which may contribute a phonetic element) with 黒 (black), reflecting the use of a black substance for eyebrow makeup.
The top 代 suggests a person, and the bottom 黒 means black. Imagine a person applying black pigment to their eyebrows: that's 黛.
For タイ, picture a person tying a black ribbon around their eyebrows: tie -> タイ, and the black ribbon darkens the brows.