One mallu word for peanut is കപ്പലണ്ടി - a combination of കപ്പല് (ship) and അണ്ടി (nut). Indicating that peanuts were introduced by traders who came by the sea.
Another mallu word is നിലക്കടല - a combination of നിലം (ground) and കടല (nut, legume). This indicates how peanuts are cultivated. Interestingly, peanuts are also called groundnuts in English.
So I am tempted to hypothesize that കപ്പലണ്ടി is an older word than നിലക്കടല. Unfortunately, I do not have the resources to verify my claim.