§102. Nouns wanting in the Singular

Some nouns of the above classes (§ 101. 1-4), have a corresponding singular, as noun or adjective, often in a special sense:

• As noun, to denote a single object: as, Bacchānal, a spot sacred to Bacchus; optimās, an aristocrat.
• As adjective: as, Catō Mâior, Cato the Elder.
• In a sense rare, or found only in early Latin: as, scāla, a ladder, valva, a door; artus, a joint.