Dwelly has ròmhan and ròmhanaich as a groan, and also as wild talk, raving.
Ròmhan tends to be used to describe the last dying groan of a man or beast. Here’s a vivid anecdote from the Cape Breton periodical Mac-Talla:
“When we were about three hundred yards from the cattle closest to us, we saw a sight I will never in my life forget. A snake, about 12 or 15 feet long, jumped out of a tree and in the blink of an eye wound itself three times around one of the cows. The poor beast let out one pitiful ròmhan when the snake tightened itself around his chest. We clearly heard the sound of his bones as its grip gradually tightened. I reckon it took five minutes to crush every bone in the chest of the poor beast. When it was sure that every bone was properly crushed, the snake started to swallow the cow without even chewing.”
Everybody I spoke to thought immediately of ròmhanaich na samhna: “the sound of the shore – ròmhanaich, when the weather is right” [South Uist]. “The sound of the shore, and mostly because bad weather is on its way.” [South Uist] “When the day is fading earlier, and the night is coming in.” [Eriskay] This sound was not at all frightening or unpleasant.