A feminine ending is a line in verse where the last syllable is slack. For example, the first four lines of Hamlet's famous "to be or not to be" monologue all have feminine endings.
To be, or not to be--that is the question:
Whether 'tis nobler in the mind to suffer
The slings and arrows of outrageous fortune
Or to take arms against a sea of troubles
And by opposing end them. To die, to sleep--
If you read that passage aloud, you'll see that there's a clear contrast between the first four lines and the fifth line. This is because the first four lines have feminine endings, while the fifth line does not.
What are some good gender-neutral alternatives to the phrase "feminine ending"?