[*] 105. Nouns that vary in Declension are called heteroclites. 1 [*] a. Colus (F.), distaff; domus (F.), house (see § 93), and many names of plants in -us, vary between the Second and Fourth Declensions. [*] b. Some nouns vary between the Second and Third: as, iūgerum , -ī, -ō, ablative -ō or -e, plural -a, -um, -ibus; Mulciber, genitive -berī and -beris; sequester, genitive -trī and -tris; vās , vāsis , and (old) vāsum , -ī (§ 79. e). [*] c. Some vary between the Second, Third, and Fourth: as, penus , penum , genitive penī and penoris , ablative penū. [*] d. Many nouns vary between the First and Fifth (see § 98. c). [*] e. Some vary between the Third and Fifth. Thus, requiēs has genitive -ētis, dative wanting, accusative -ētem or -em, ablative -ē (once -ēte); famēs, regularly of the third declension, has ablative famē (§ 76. N. 1), and pūbēs (M.) has once dative pūbē (in Plautus). [*] f. Pecus varies between the Third and Fourth, having pecoris , etc., but also nominative pecū , ablative pecū; plural pecua, genitive pecuum . [*] g. Many vary between different stems of the same declension: as, femur (N.), genitive -oris, also -inis (as from † femen ); iecur (N.), genitive iecinoris, iocinoris , iecoris; mūnus (N.), plural mūnera and mūnia .
[*] 105. Nouns that vary in Declension are called heteroclites. 1 [*] a. Colus (F.), distaff; domus (F.), house (see § 93), and many names of plants in -us, vary between the Second and Fourth Declensions. [*] b. Some nouns vary between the Second and Third: as, iūgerum , -ī, -ō, ablative -ō or -e, plural -a, -um, -ibus; Mulciber, genitive -berī and -beris; sequester, genitive -trī and -tris; vās , vāsis , and (old) vāsum , -ī (§ 79. e). [*] c. Some vary between the Second, Third, and Fourth: as, penus , penum , genitive penī and penoris , ablative penū. [*] d. Many nouns vary between the First and Fifth (see § 98. c). [*] e. Some vary between the Third and Fifth. Thus, requiēs has genitive -ētis, dative wanting, accusative -ētem or -em, ablative -ē (once -ēte); famēs, regularly of the third declension, has ablative famē (§ 76. N. 1), and pūbēs (M.) has once dative pūbē (in Plautus). [*] f. Pecus varies between the Third and Fourth, having pecoris , etc., but also nominative pecū , ablative pecū; plural pecua, genitive pecuum . [*] g. Many vary between different stems of the same declension: as, femur (N.), genitive -oris, also -inis (as from † femen ); iecur (N.), genitive iecinoris, iocinoris , iecoris; mūnus (N.), plural mūnera and mūnia .