From pithanos (persuasive) and logos (word). Persuasive, plausible-sounding but deceptive argumentation. Paul warns the Colossians against being deceived by fine-sounding arguments.
Paul warns: 'I tell you this so that no one may deceive you by fine-sounding arguments' (Colossians 2:4). False teaching rarely sounds obviously wrong — it sounds plausible. The danger is not absurd claims but reasonable-sounding alternatives to the gospel. Discernment requires knowing truth so well that counterfeits are immediately recognized.