Definition of ordo

< ordnance

ordonnance >

or·do    (ôrd) KEY 

NOUN:
Roman Catholic Church pl. or·di·nes  (-d-nz) KEY  or or·dos

An annual calendar containing instructions for the Mass and office to be celebrated on each day of the year.

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ETYMOLOGY:
Medieval Latin rd, from Latin, order; see ar- in Indo-European roots