means A fixed outdoor pipe-fitting connected to a water main, from which firefighters draw water to fight fires.

from Born in the early 19th century from the Greek 'hydōr,' meaning water — the same root that gives us 'hydrogen' and 'hydraulic.' English took the 'hydr-' element and capped it with '-ant,' the suffix that turns a thing into an agent or doer (as in 'coolant' or 'lubricant'). So the word literally names 'the water-thing,' a fittingly plain label for a fittingly plain object — a name as no-nonsense as the squat iron sentinel it describes.