It’s difficult to imagine what life would be like without the present active indicative of λύω (luō), “I loose,” or “I destroy.”

Remember what Machen says about the “movable ν:”

When -ουσι the of the third person plural of the verb comes either before a vowel or at the end of a sentence, a ν, called movable ν, is added to it. Thus βλέπουσιν ἀποστόλους. Sometimes the movable ν is added even before a word that begins with a consonant. Thus either λύουσι δούλους or λύουσιν δούλους is correct. It must not be supposed that this movable ν occurs at the end of every verb form ending in a vowel when the next word begins with a vowel. On the contrary, it occurs only in a very few forms, which must be learned as they appear.

[J. Gresham Machen, New Testament Greek for Beginners, (Toronto, Ontario: The Macmillan Company, 1923; 1951), 27 (§44).]

Isn’t Koinē Greek (Κοινὴ Ἑλληνική) fun?