nonagesimal
/ˌnɒnəˈdʒɛsɪml/noun
Astronomy and Astrology. The point of the ecliptic which is highest above the horizon at any given time, being 90 degrees round the ecliptic from the point at which it intersects the horizon.
Origin
Early 18th century (in an earlier sense). From classical Latin nōnāgēsimus ninetieth (from nōnāgintā ninety (from novem nine + -gintā, suffix forming cardinal numerals from thirty to ninety, related to decem ten: see decem-) + -ēsimus, extended form (after vīcēsimus) of -simus, suffix used to form ordinal numerals) + -al.