English
ellipsometer
From ellipse + -o- + -meter.
Formed from ellipse + -o- + -meter
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 an instrument that uses polarized light to investigate the surface layers of semiconductor wafers etc. Used in ellipsometry.
Language periods are conventional ranges, not dates for this word.
Etymograph / ellipsometer