The full form of W4M is woman for man
It stands for woman for man and means that a female is looking for a man. She could be expressing an interest in men for dating, or for a casual hookup. You can find anything you want using this basic string of letters.

The acronym W4M often appears on dating websites like Tinder andMatch.com, or in personal ads like Craigslist.

Other Meanings
※W4M§ can also mean:

Woman for men (one woman and more than one man)
Woman seeking man (one woman and one man)
Woman seeking men (one woman and more than one man)
Women seeking man (more than one woman and one man)
Women seeking men (more than one woman and more than one man)
Women for man (one woman, one man)
Women for men (one woman, more than one man)
Women looking for men (more than one woman, more than one man)
Women looking for man (more than one woman, one man)
Woman looking for man (one woman, one man)
Woman looking for men (one woman, more than one men)
※W4M§ doesn＊t just refer to a female＊s interest in a male. It can also stand for ※works for me,§ ※wait for me.§

Similar Slang Words
Just as there are variations for women and men (※W4M§), there are also variations for men and women (※M4W§). Here are a few other personal ad lingoes you might see.

M4W 每 Man for Woman
M4M 每 Man for Man
W4W 每 Woman for Woman
MSM 每 Man Seeking Man
MSW 每 Man Seeking Woman
WSM 每 Woman Seeking Man
WSW 每 Woman Seeking Woman
F4M 每 Female for Male
M4F 每 Male for Female

Conversation Examples
Conversation Example using ※W4M§
Fnnygurl69: w4m CE 2nite 10 to 2 hmu with pix & HWP
Ladiesman00: hey @fnnygurl69 hyd im 22 5＊9 and 190 lbs I＊m a personal trainer
Fnnygurl69: hi #ladiesman00. Ur cute! Meet for drinks at Lagoon?
Ladiesman00: 1030?
Fnnygurl69: cu soon