Noun
(historical) A traditional short Spanish unit of length, usually about equal to 1.75 cm.
(historical) A traditional short Portuguese unit of length, usually about equal to 1.8 cm.
Source: en.wiktionary.orgWhereupon grandmother could often be heard to mutter, "como anillo al dedo," meaning that our recurrent recalcitrance and my father’s perennial rebukes were two things that just went together; one was the natural consequence of the other. Source: Internet
But once all the pieces have fallen into place — usually not until the day before classes are scheduled to begin — it’s another case of como anillo al dedo. Source: Internet