ἅμα

Etymology
From the zero-grade of.

The dative is from the PIE comitative-instrumental.

Adverb

 * 1) marking the simultaneous occurrence of two events: simultaneously, at once, at the same time
 * 2) marking general concurrence (spatial, temporal, etc: together)

Preposition

 * 1) at the same time with
 * 2) together with