LEO, LEON, LEOUN, LYOUN. Leo the Lion is the fifth sign of the zodiac and both day house and night house of the sun (Tetrabiblos I.17). The hot and dry sign, it lies in the northern hemisphere between Cancer and Virgo (Confessio Amantis VII.1067-1072).

Saturn is particularly destructive when he enters Leo, KnT 2461-2462. The sun has left the "angle meridional" or the tenth mansion, and the Lion is ascending with his Aldiran; that is, the time is very much past noon, SqT 263-267. The Lion begins to rise at noon and is fully risen at about a quarter to three. Aurelius asks Phebus to request Lucina, his sister the moon, to hold the waters over the rocks when the next opposition takes place and the sun is in Leo, FranklT 1055-1061. Since the sun controls the moon and both move at the same rate, the resulting flood tide could last as long as two years. Ector decides to fight the Greeks on the day when Phebus is in the breast of Hercules's Lion, Tr IV.29-35; thus the sign is identified as the Nemean Lion. The time is either the latter part of July or the beginning of August. Skeat (II: 485) suggests that since the sun is in the breast of Leo or near Regulus, the brightest star of the sign, the time is the first week of August. Criseyde promises to return before the moon passes out of Aries, beyond Leo, Tr IV.1592. The moon passes out of Leo as Criseyde prepares for bed instead of returning to Troy, Tr V.1019. Leo is the fifth sign of the zodiac, Astr I.8.3; it lies directly opposite Aquarius, Astr II.6.17, and is the sovereign or western sign that Taurus obeys, Astr II.28.7. [Aldiran: Ercules: Saturne]

Leo, the Latin variant, appears in the prose of the Astrolabe; Leon appears once medially, SqT 265; Leoun occurs twice medially, Tr IV.1592, V.1019, and in the prose of the Astrolabe; once in final rhyming position, FranklT 1058; Lyoun occurs once in final rhyming position, Tr IV.32. Leon, Leoun, Lyoun are variants of OF Lion and Anglo-Norman Leun.