from
The Collaborative International Dictionary of English v.0.48
Grunt \Grunt\ (gr[u^]nt), v. t. [imp. & p. p. {Grunted}; p. pr.
& vb. n. {Grunting}.] [OE. grunten; akin to As. grunian, G.
grunzen, Dan. grynte, Sw. grymta; all prob. of imitative; or
perh. akin to E. groan.]
To make a deep, short noise, as a hog; to utter a short groan
or a deep guttural sound.
[1913 Webster]
Who would fardels bear,
To grunt and sweat under a weary life. --Shak.
[1913 Webster]
{Grunting ox} (Zool.), the yak.
[1913 Webster]