The Dual

---

Introduction

PIE had three numbers: singular, plural, and dual, used for things that come in twos, like body parts. The dual had largely been lost in Classical Greek.

The nominative and accusative dual have the same form, and the genitive and dative dual have the same form:

	1st declension (-α/)	2nd declension (-ο/)	3rd declension
Nominative and Accusative	/ø θεά/ø > θεά	/L ὀφθαλμό/L > ὀφθαλμώ	/ε πόδ/ε > πόδε
Genitive and Dative	/ιν θεά/ιν > θεαῖν	/ιν ὀφθαλμό/ιν > ὀφθαλμοῖν	/οιν πόδ/οιν > ποδοῖν*

*Monosyllabic bases keep the accent on the last syllable in the genitive and dative. Thus genitive/dative πόδ/οιν > ποδοῖν.

---

Intermediate

The dual number was used in Homeric Greek, but not consistently: a dual noun could take a singular or plural verb; a dual verb a singular or plural noun. For more on the dual in Homer, see https://dcc.dickinson.edu/grammar/monro/dual

In Classical Greek, the dual exists mostly in frozen forms.

A noun one commonly finds in the dual is χέρ/, ἡ. When the base lengthens, like in the nominative singular, it lengthens to χείρ, not *χήρ (χέρ/Lø) — there is a Greek word χήρ, but it means “hedgehog.” When the noun’s final form is disyllabic, which is typically the case, if the last syllable (with the case marker) is short, the first syllable (with the base χέρ/) lengthens. So the genitive and dative dual is χέρ/οιν > χεροῖν but the nominative and accusative dual is χέρ/ε > χεῖρε. (Occasionally but rarely poets will use χειροῖν instead of χεροῖν if it is helpful for the meter.)

Markers of the dual are frozen in some Indo-European languages in words like English “two” and “twin,” Ancient Greek δύο or δύω (“two”), and Latin duo (“two”) and ambo (“both sides”).

---

Vocabulary for this lesson (see here for the full lexicon)