From Proto-Indo-European *ḱes- (“to cut”) + *-trom. This word shows a zero-grade root and epenthetic insertion of -a-.
*kastrom n
The original declension, given the presence of *-trom:
singular | plural | |
---|---|---|
nominative | *kastrom | *kastrā |
vocative | *kastrom | *kastrā |
accusative | *kastrom | *kastrā |
genitive | *kastrosjo, *kastrī | *kastrom |
dative | *kastrōi | *kastrois |
ablative | *kastrōd | *kastrois |
locative | *kastrei | *kastrois |
In Sabellic however, this word was secondarily transformed into a u-stem:
singular | plural | |
---|---|---|
nominative | *kastrus | *kastrowes |
vocative | *kastrus | *kastrowes |
accusative | *kastrum | *kastruns |
genitive | *kastrous | *kastrwom |
dative | *kastrowei | *kastruβos |
ablative | *kastrūd | *kastruβos |
locative | *kastrou | *kastruβos |
The term may have undergone a semantic shift from the original Proto-Indo-European notion of cutting to mean "cut off part or section." From this new meaning, the term may have developed to mean "fenced off area," before further shifting to refer to a type of camp in Latin. The notion that the term originally referred to cutting is supported by Latin castrō (“to amputate, castrate”), which may derive from Proto-Italic *kastrāō, which itself may have been a denominative verb to an instrumental noun also reconstructible as *kastrom.