Webster's Collaborative New Word Dictionary - W
wankstain (n.): a semen stain.
weak sauce (adj.): Something that is of a poor or disappointing standard or quality.
wet market (n.): a market that sells perishable items (such as fresh meat and produce) and sometimes live animals which are often slaughtered on-site.
wine o'clock (n.): An appropriate time of day for starting to drink wine.