groan 
(grōn)
(grōn)v. groaned, groan·ing, groans
v.intr.
1. To voice a deep, inarticulate sound, as of pain, grief, or displeasure.
2. To make a sound expressive of stress or strain: floorboards groaning.
v.tr.
To utter or express with groans or a groan.
n.
The sound made in groaning.
[Middle English gronen, from Old English grānian.]
groaner n.
groaning·ly adv.