What is the meaning of Simp?

A simple person lacking common sense; a fool or simpleton.

Someone who is not worthy of respect.

A man who foolishly overvalues and defers to a woman, putting her on a pedestal.

Someone who foolishly overvalues someone else and defers to them, putting them on a pedestal.

An advocate for an ideology or cause.

To be especially deferential to and emotionally vulnerable with a woman, often with the intent of receiving sexual gratification.

To obsequiously praise or admire.

To reminisce melancholically; to recall once fond memories now tinged with sadness, especially regarding a former lover.

Abbreviation of simplified.

Source: wiktionary.org