2. To lose consciousness (3rd person). Used when describing a general nonspecific occurrence.
3. To lose consciousness (1st person Royal). Used exclusively by members of the hereditary ruling families of English speaking countries to describe what happened to them when they were last playing "Who's the Tampon, Camilla?"
4. (imperative) An injunction given, in the 2nd person singular, to knock out one of whatever is to be knocked out.
2. "Billy, have you been knocking one out over here? The smell in this room is enough to knock one out."
3. "One has been knocking one out, one must pronounce oneself feeble as the strain of so doing has been enough to knock one out."
4. When two Scouse teenagers - wearing Kappa tracksuits and sporting formidable Scouse 'fro hairstyles - are going around smashing windows of buildings, and come across a 14th century church with several irreplaceable Gothic stained glass windows depicting scenes from the life of the Virgin Mary, passersby may often hear one Scouse youth inquire of the other whether the ecclesiastical image is worthy to be spared from their brand of urban renewal. The response is frequently "A-right, we'll just knock one out, then, an' leave the rest, okay Barry?" (HMB's Guide to Liverpool Nightlife, Fodders and Stoughton, 1993)