English
hemiellipse
From hemi- + ellipse.
Proto-Indo-European *leykʷ- ‘to leave behind’
…
Ancient Greek ἐλλείπω ‘to fall short, omit’
Ancient Greek ἔλλειψις ‘a falling short, defect’
Latin ellīpsis
French ellipse ‘ellipse (the locus of a point such that the…’
English ellipse
Today it means
noun A shape obtained by cutting an ellipse in half along one of its axes
Language periods are conventional ranges, not dates for this word.
Etymograph / hemiellipse