Where does “demicircular” come from?

demicircular (English) comes from English circular, from Middle English circuler, from Old French circulier, from Latin circulāris, from Latin circulus, from Latin -ulus, from Proto-Italic -olos, from Proto-Italic -elos — Forms agent nouns from verbal roots.

Ancestry of “demicircular”, step by step

demicircular traces back through two separate lines of ancestry.

via English circular

StepLanguageWordMeaning
1EnglishcircularOf or relating to a circle; In the shape of, or...
2Middle Englishcirculer
3Old Frenchcirculier
4Latincirculāriscircular, round
5Latincirculuscircle; An orbit; A ring, hoop
6Latin-ulusUsed to form a diminutive of a noun, indicating...
7Proto-Italic-olos
8Proto-Italic-elosForms desubstantival and deadjectival diminutive nouns
9Proto-Indo-European-e-lós
10Proto-Indo-European-lósForms agent nouns from verbal roots

via English demi

StepLanguageWordMeaning
1EnglishdemiAlternative spelling of demy; A fifty pence...
2Middle Englishdemihalf, half-sized, partial
3Anglo-Normandemihalf
4Latindīmidiushalf
5Latinmediusmiddle; half; moderate
6Latinlocusplace, spot; a passage of literature; "in the...
7Old Latinstlocus
8Proto-Italicstlokos
9Proto-Indo-Europeanstel-to put, to place; to locate
Every word from Proto-Indo-European -lós
demicircular — Etymology, Origin & Word History | Etymology Explorer