Bill Mounce

For an Informed Love of God

ὁ means “the.”

“Are you ὁ teacher of Israel, and you do not understand these things?” (John 3:10).

Mounce's Expository Dictionary (abridged): 

Adjective: ὁ (ho), GK G3836 (S G3588, G5120]), 19,867x. The prepositive article corresponds somewhat to the english article “the,” but it can also function as the demonstrative (“this, that”) or personal pronoun (“he, she, it”) and also a correlative, ὁ μὲν ... ὁ δέ, the one ... the other (Phil. 1:16, 17; Heb. 7:5, 6, 20, 21, 23, 24). It can aid it turning an adjective or participle into a substantive.