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apsidiole

American  
[ap-sid-ee-ohl] / æpˈsɪd iˌoʊl /

noun

  1. a small apse, especially one attached to a larger apse or a transept.


Etymology

Origin of apsidiole

1885–90; < French absidiole, equivalent to abside apsis (< Medieval Latin absid-, stem of absis ) + -i- -i- + -ole -ole 1