The Hebrew noun mirmah means deceit, treachery, or fraud. Occurring about 39 times in the OT, it describes deceptive speech, fraudulent business dealings, and treacherous betrayal. It is the opposite of emet (truth) and tamim (integrity).
Mirmah is consistently condemned in Scripture as incompatible with covenant faithfulness. God hates deceitful tongues (Proverbs 12:17; Psalm 5:6). The contrast between mirmah and emet (truth) is central to the OT ethical framework. Psalm 24:4 says only those with no mirmah on their lips can ascend to God's holy mountain. Jesus is the incarnation of emet — 'no deceit was found in his mouth' (1 Peter 2:22, citing Isaiah 53:9).