I have learned the word as αποτυχαίνω not as αποτυχάνω. I can not find the latter in the dictionary and my spelling check marks it as wrong. My native Greek wife now tells me it is ancient Greek - can we please stick to the modern forms, otherwise it gets more confusing than it already is.
Αποτυγχάνω is the most common Modern form. Αποτυχαίνω is an alternative form of αποτυγχάνω and not the other way around, and personally as a Modern Greek native speaker, I've never used it. It actually sounds uneducated. This course teaches modern greek and modern greek only.
I notice you have a spelling error here. Perhaps that's why you didn't find it in the dictionary. I just check this set of 7 Modern Greek dictionaries and they all have "αποτυγχάνω".
One shows "αποτχαίνω" but as Troll says it's not used and we only teach modern Greek.
Noticed the spelling error - thx for that, but αποτυγχάνω still is not in Pons dictionary. I have talked to several other Greek persons now and they all agree that αποτυχαίνω is by far the more common word.
("γχ"=light "ν"+"χ" sound≈"νχ")
They are clearly quite different words. I do not know why I consistently confuse them.
It happens! But anyway, it's more likely to encounter the verb "failed" rather than "fail". In Greek, the conjugation of the verb "to fail" in the Past Simple tense is:
Thanks. The simple past is something I could use lot more practice with. Something to think about, if you guys do an expansion of the tree.