χρή

Etymology
Apparently from a, , with relation to other roots uncertain. Traditional theories connecting the root to 🇨🇬 (whence ) or to 🇨🇬 (which itself is of disputed origin, perhaps from 🇨🇬 according to de Vaan) are deemed unconvincing by Beekes.

Originally probably a neuter noun in plural, but used always as a verbal expression by omission of copula ἐστί or "crasis" of χρὴ with it.

Verb

 * 1)  have to, ought, should

Inflection

 * Present indicative: (from χρή ἐστι)
 * Present infinitive: (from χρὴ εἶναι)
 * Imperfect indicative:, and originally (from χρὴ ἦν).
 * Present subjuntive: (from χρὴ ᾖ).
 * Present optative: (from χρὴ εἴη).
 * Present participle, mostly as noun: (from χρὴ ὄν > χρηόν > χρεών: transfer of vowel quantity).
 * Future indicative: and originally  (from χρὴ ἔσται, which in some codexes is sometimes erroneously written χρῆσται and even χρῆσθαι).