Where does “semimeridian” come from?

semimeridian (English) comes from English meridian, from Middle English meridian, from Middle French meridien, from Latin meridianus, from Latin merīdiēs, from Latin medīdiēs, from Latin diēs, from Proto-Italic djēm — to be bright; sky, heaven.

semimeridian (English): The intersection of a surface of revolution and a half-plane through its centre

Definitions

  1. The intersection of a surface of revolution and a half-plane through its centre

Ancestry of “semimeridian”, step by step

semimeridian traces back through two separate lines of ancestry.

via English meridian

StepLanguageWordMeaning
1EnglishmeridianThe south; Midday, noon; A great circle passing...
2Middle Englishmeridian
3Middle Frenchmeridienmidday; the south; celestial meridian
4Latinmeridianusmidday, noon; southern
5Latinmerīdiēsmidday, noon
6Latinmedīdiēs
7LatindiēsA day, particularly
8Proto-Italicdjēmaccusative singular of *djous
9Proto-Italic*djous
10Proto-Indo-Europeandyḗwssky, heaven; sky god
11Proto-Indo-Europeandyéwssky, heaven
12Proto-Indo-Europeandyew-to be bright; sky, heaven

via English semi

StepLanguageWordMeaning
1EnglishsemiA semi-detached house; A semitrailer; a...
2Englishsemi-half; partial, incomplete; somewhat, rather,...
3Latinsēmi-half
4Proto-Indo-Europeansēmihalf; partially
Every word from Proto-Indo-European dyew-Every word from Proto-Indo-European dyéwsEvery word from Proto-Indo-European dyḗws