α β γ δ ε ζ θ κ λ μ ν ξ ο π σ τ υ φ χ ψ ἀ ἁ ἄ ἅ ἆ ἐ ἑ ἔ ἕ ἠ ἡ ἤ ἥ ἦ ἧ ἰ ἱ ἴ ἵ ἶ ὀ ὁ ὄ ὅ ὑ ὕ ὗ ὠ ὡ ὤ ὥ ὦ ὧ ᾄ ᾅ ᾠ ῥ

Letter ἦ has 3 occurences.

Count	word	def
2	ἦθος	usage, i.e. (plural) moral habits
0	ἦν	I (thou, etc.) was (wast or were)
5	ἦχος	a loud or confused noise ("echo"), i.e. roar; figuratively, a rumor