From Longman Dictionary of Contemporary Englishtamptamp /tæmp/ (also tamp down) verb [transitive always + adverb/preposition] PUSHto press or push something down by lightly hitting it several times The old man tamped down the tobacco with his thumb.→ See Verb table
Examples from the Corpus
tamp• As well as surprise, she had heard irritation tamped down in Vitor's voice.• Before you start laying the bricks, tamp down the soil underneath.• What wouldn't burn still remained: bare walls muffled with incongruous tapestries, flooring tamped over with carpets.• Huy's job was to tamp this second layer down on to the first.Origin tamp (1800-1900) Perhaps from tampion, tampin “plug, cover” ((15-20 centuries)), from French tampon; → TAMPON