What does apsidal mean?
Apsidal is an adjective describing anything related to an apse — the semicircular or polygonal recess that terminates the eastern end of many churches, basilicas, and temples. An apsidal chapel, apsidal vault, or apsidal east end refers to this distinctive curved or faceted closing feature, common in Romanesque and Gothic architecture. The word also has a second life in astronomy, where it pertains to the apsides of an orbit: the point closest to the orbited body (periapsis) and the farthest (apoapsis). Astronomers speak of the apsidal line joining these points and of apsidal precession, the gradual rotation of that line within the orbital plane — famously observed in Mercury's orbit. Derived ultimately from the Greek hapsis, meaning 'arch' or 'vault', apsidal is a precise technical term encountered chiefly in architectural description and celestial mechanics rather than casual conversation.
Of or relating to an apse; having the form of an apse.
"The abbey's apsidal terminus dates from the twelfth century."
Of or relating to the apsides of an orbit.
"General relativity accounts for the anomalous apsidal precession of Mercury."
The same word describes both the rounded east end of a medieval cathedral and the slow drift of Mercury's orbit that helped confirm Einstein's theory of relativity.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of apsidal
Apsidal derives from Late Latin apsis, borrowed from Greek hapsis, meaning 'arch' or 'vault', which itself may relate to haptein, 'to fasten'. The architectural noun apse entered English in the Renaissance period, and the adjective apsidal followed as writers described buildings terminating in an apse. In astronomy, the same root produced apsis and its compounds apoapsis and periapsis, giving apsidal its orbital sense. Its cognates therefore span both architecture and celestial mechanics.
Related word forms
How apsidal is actually used
A technical term used mainly in architectural history and celestial mechanics; rare in everyday speech.
Easily confused with apsidal
"Apical" means relating to the apex or tip of something, while "apsidal" relates to an apse of a building or the apsides of an orbit.