To smear, coat, or plaster; metaphorically, to forge lies or fabricate falsehood. The word bridges the physical act of plastering a wall (covering what is underneath) with the moral act of covering truth with deception. Ezekiel uses it powerfully against false prophets who 'plaster' over dangerous cracks with whitewash.
Taphal is God's word against religious deception. When false prophets proclaimed 'Peace!' while the wall was crumbling, they taphal — plastered over the cracks (Ezekiel 13:10-15). Jesus echoed this image with 'whitewashed tombs' (Matthew 23:27). The word warns that covering problems with religious language doesn't fix them — it makes the eventual collapse worse.