To let fall, or the smallest unit of liquid — release downward; in a base, the removal that is KP1's hand alone.
Old English dropa (a drop of liquid), related to dropian/dreopan (to drip); a small measured release, or the letting-fall of a larger thing.
A letting-fall, or the smallest measured unit of a liquid — a release downward either way. Where a base is concerned, this is the one removal that belongs to a single hand alone.