Origin of dottleMiddle English dotelle, variant, variety of dosel, dossil
Origin of dottleFrom dot1, lump (obsolete).
From Middle English dottel, dottelle (“a plug or tap of a vessel”), a diminutive of Old English dott (> English dot (“a point”)), equivalent to dot + -le. Related to Old English dyttan (“to stop up, clot”), Dutch dot (“a knot, lump, clod”), Low German Dutte (“a plug”). More at dit.