11 letters · 15 points in Scrabble
verb make impure
verb make radioactive by adding radioactive material
originFirst attested in the early 15ᵗʰ century, in Middle English; from Middle English contaminaten (“to defile; to infect with desease”), from contaminat(e) (“sullied, defiled; infected with desease”, also used as the past participle of contaminaten) + -en (verb-forming suffix), from Latin contāminātus, the perfect passive participle of contāminō (“to touch together, blend, mingle, corrupt, defile”)…
Etymology from Wiktionary, CC BY-SA 3.0