出典:Wiktionary
From Middle English gronen, granen, from 古期英語 grānian (“to groan; lament; murmur”), from Proto-West Germanic *grainōn, from Proto-Germanic *grainōną (“to howl; weep”), from Proto-Germanic *grīnaną (“to whine; howl; whimper”).
Cognate with Dutch grijnen, grienen (“to cry; sob; blubber”), German Low German grienen (“to whimper; mewl”), German greinen (“to whine; whimper”), Swedish grina (“to howl; weep; laugh”).
The noun is from Middle English gron, grone, from the verb.
groan (三人称単数 現在形 groans, 現在分詞 groaning, 過去形および過去分詞形 groaned)