Why is the ninth month called September?
mid-14c., from Latin curtus "(cut) short, shortened, incomplete," from PIE root *(s)ker- "to cut" (see short (adj.)). Sense of "rude" is first recorded 1831. The Latin word was adopted early into most Germanic languages (cf. Icelandic korta, German kurz, etc.) and drove out the native words based on Proto-Germanic *skurt-, but English retains short.