Webster's Revised Unabridged Dictionary · 1913

Gad

Gad , noun

[Old English gad, Icelandic gaddr goad, sting; akin to Swedish gadd sting, Gothic gazds, German gerte switch. See Yard a measure.]

1.
The point of a spear, or an arrowhead.
2.
A pointed or wedge-shaped instrument of metal, as a steel wedge used in mining, etc.
I will go get a leaf of brass, And with a gad of steel will write these words. — Shakespeare
3.
A sharp-pointed rod; a goad.
4.
A spike on a gauntlet; a gadling. — Fairholt
5.
A wedge-shaped billet of iron or steel. [Obsolete]
Flemish steel... some in bars and some in gads. — Moxon
6.
A rod or stick, as a fishing rod, a measuring rod, or a rod used to drive cattle with. [Provincial English Local, United States] — Halliwell. Bartlett
Collocations (1)
Upon the gad , upon the spur of the moment; hastily. [Obsolete] All this done upon the gad! — Shakespeare

Gad , intransitive verb

[Probably from gad, n., and orig. meaning to drive about.]

To walk about; to rove or go about, without purpose; hence, to run wild; to be uncontrolled.
The gadding vine. — Milton
Why gaddest thou about so much to change thy way? — Jer. ii. 36