muĝi

A word that sounds like the thing. Muĝi is the deep, sustained, open-throated noise: a cow lowing, the sea under a gale, the wind in a chimney, a crowd a long way off. Esperanto has a small collection of these imitative verbs and they are unusually easy to remember because the root does half the work - see interjections and onomatopoeia for the family.

The animal-noise system is more organised than English's. English makes you learn low, bleat, bark, neigh, bray, mew as unrelated words. Esperanto has bleki as the general verb - to make the cry proper to one's species - so la ŝafo blekas covers a sheep bleating without a new root, and you specify the animal if it is not obvious. Alongside it sit the specific imitative verbs for particular noises: muĝi for the deep bellow, boji for a dog's bark, bleki when you do not care which. The general-plus-specific arrangement is the whole design of Esperanto vocabulary in miniature.

Weather and machines get it too. La ventego muĝas is a gale howling; la motoro muĝas is an engine roaring. English switches verbs between these - wind howls, engines roar, seas thunder - and Esperanto simply does not, which is one of those places the language is genuinely easier rather than merely different. The noun is muĝo for one such noise and muĝado for the continuous sound of it, with -ad- doing what it always does - see aspect affixes.