cippus.

Seemingly from a Proto-Italic *keipos (where Latin cīpus would be the older form), likely related to scīpiō, of unclear further origin. De Vaan derives the word from Proto-Indo-European *(s)ḱéypos (“pole, stick”), connecting it to Sanskrit शेप (śepa, “penis, tail”). However, the irregular alternation between the form with short ĭ and geminate pp versus that with long ī with singular p is difficult to explain; it could indicate contamination from another Italic dialect or borrowing from a substrate language, or it could be a normal Latin sound law seen also in littera from lītera. Not related to Latin scāpus, English shaft, Ancient Greek σκήπτω (skḗptō), despite some such suggestions.