tetradium
Could not find Tetradio in Logeion dictionaries.
Tetradio Noun: neuter ablative singular, Noun: neuter dative singular of tetradium
tē̆trădĭum, ii, n., = τετράδιον,
- the number four, a quaternion, tetrad, Col. 3, 20, 3; Sen. Contr. 5 praef.
tĕtrădĭum ou tĕtrădēum, ī, n. (τετράδων et τετραδεῖον), le nombre quatre : Sen. Rhet. Contr. 10, præf. 12 ; Col. Rust. 3, 20, 2.