From Middle English bolken (“to belch, vomit”), from Old English bealcan (“to belch, utter, bring up, sputter out, pour out, give forth, emit, come forth”), from Proto-Germanic *belkaną (“to belch”), ultimately imitative. Cognate with Dutch balken & bulken (“to bellow”), German bölken (“to roar”). See also belch.
- (obsolete) To burp.
- (Scotland) To retch or vomit.
- 1997, Alan Warner, Movern Callar 
- I was going to boak: I made the window and opened it but most of the sickness hit the window-sill in a heap.
- 1999, Ian Rankin, Black and Blue 
- He’d skipped breakfast—didn’t like the idea of boaking it back up on the flight.
- 1999, Kate Atkinson, Behind the Scenes at the Museum 
- I think it was at this moment that Patricia lurched from the table, informing everyone that she was going to be sick and indeed was as good as her word, throwing up before reaching the door (‘Heinrich, fetch a clout — the lassie’s boaked!’).
- 2020, Douglas Stewart, Shuggie Bain.
- She had to keep stopping to spit gobbits of rising boak into sinks and old tea mugs.
- For quotations using this term, see Citations:boak.