Webster's Revised Unabridged Dictionary · 1913

Grin

Grin , noun

[Anglo-Saxon grin.]

A snare; a gin. [Obsolete]
Like a bird that hasteth to his grin. — Remedy of Love

Grin , intransitive verb

[Old English grinnen, grennen, Anglo-Saxon grennian, Swedish grina; akin to Dutch grijnen, German greinen, Old High German grinan, Danish grine. r35. Compare Groan.]

1.
To show the teeth, as a dog; to snarl.
2.
To set the teeth together and open the lips, or to open the mouth and withdraw the lips from the teeth, so as to show them, as in laughter, scorn, or pain.
The pangs of death do make him grin. — Shakespeare

Grin , transitive verb

To express by grinning.
Grinned horrible a ghastly smile. — Milton

Grin , noun

The act of closing the teeth and showing them, or of withdrawing the lips and showing the teeth; a hard, forced, or sneering smile. — I.Watts
He showed twenty teeth at a grin. — Addison