Blowhole1. (n.) A cavern in a cliff, at the water level, opening to the air at its farther extremity, so that the waters rush in with each surge and rise in a lofty jet from the extremity.
2. (n.) A nostril or spiracle in the top of the head of a whale or other cetacean.
3. (n.) A hole in the ice to which whales, seals, etc., come to breathe.
4. (n.) An air hole in a casting.
Thesaurus Entries
air duct, air hole, air passage, air shaft, air tube, airway, armhole, avenue, breathing hole, bullet-hole, bunghole, channel, chute, cringle, deadeye, debouch, door, egress, emunctory, escape, estuary, exhaust, exit, eye, eyelet, floodgate, flume, gasket, grommet, guide, keyhole, knothole, loop, loophole, louver, louverwork, manhole, mousehole, naris, nostril, opening, out, outcome, outfall, outgate, outgo, outlet, peephole, pigeonhole, pinhole, placket, placket hole, pore, port, porthole, punch-hole, sally port, shaft, sluice, spilehole, spiracle, spout, tap, touchhole, transom, vent, ventage, venthole, ventiduct, ventilating shaft, ventilator, vomitory, way out, weir, wind tunnel