ChristianAnswers.Net WebBible Encyclopedia

pillar

…used to support a building (Judg. 16:26, 29)

…as a trophy or memorial (Gen. 28:18; 35:20; Ex. 24:4; 1 Sam. 15:12, Authorized Version, “place,” more correctly “monument,” or “trophy of victory,” as in 2 Sam. 18:18)

…of fire, by which the Divine Presence was manifested (Ex. 13:2)

The “plain of the pillar” in Judg. 9:6 ought to be, as in the Revised Version, the “oak of the pillar”, i.e., of the monument or stone set up by Joshua (24:26).