groan

Short definition from Wiktionary

Noun

1. 1
   A low, mournful sound uttered in pain or grief.
2. 2
   A low, guttural sound uttered in frustration, disapproval, or ecstasy.
3. 3
   A low creaking sound from applied pressure or weight.

Verb

1. 1
   To make a groan.
2. 2
   To seemingly creak under the strain of being heavily laden.
3. 3
   To strive after earnestly, as if with groans.