Boyd’s Bible Dictionary:
(gad, strike). A rod spiked at the end for driving oxen (Judg. 3:31); and iron-shod at the other end for cleaning plows, or even for plowing (1 Sam. 13:21).
Concise Bible Dictionary:
A long slender pole with a sharp point at one end, used for guiding and urging the oxen in plowing. It can also be used as a formidable weapon. Shamgar slew six hundred men with an ox goad (Judg. 3:31; 1 Sam. 13:21). It is applied metaphorically to the energy imparted by the words of the wise (Eccl. 12:11). The goad is alluded to in Acts 9:5; Acts 26:14, translated “pricks:” if the ox kicked against the goad, he only hurt himself the more: as do all those who oppose God.
Strong’s Dictionary of Hebrew Words:
Meaning:
from 3925; a goad for oxen
From Manners and Customs of the Bible:
Judges 3:81. Shamgar the son of Anath, which slew of the Philistines six hundred men with an ox goad.
This must have been a formidable weapon if, as is doubtless the case, the goad of that day was similar to the one now used in Palestine. It is a strong pole about eight feet long and two inches in diameter. At one end is a sharp point for pricking the oxen when their movements become intolerably slow, and at the other end is a broad chisel-like blade, which is used to clear the plowshare of the roots and thorns which impede it or of the stiff clay which adheres to it. The pointed end of this instrument is alluded to in Acts 9: 5; 26:14.