From Ralph Earle's Word Meanings in the New Testament:
"In the Greek comic writers the verb ARTUW, 'season,' referred to the seasoning with the salt of wit. But too often this degenerated into off-color jokes. Paul says that the Christian's speech should be 'with grace' or 'gracious'" (p. 362).
"Let your conversation be always gracious, and never insipid; study how best to talk with each person you meet" (Col. 4:6 NEB).