Since it came up in another thread, I must now engage in rabid pedantry.

What do you call a short verse poem made of three lines with 5, 7, 5 syllables?

The correct answer is a senryu. But there's one particular subspecies of senryu that is most famous. It is the haiku. Every haiku is a senryu, in the same way every mammal is an animal; but not every senryu is a haiku.

To be a haiku, pedantically speaking, a senryu needs three additional elements beyond the 5-7-5 pattern. (Note: poetry has a natural resistance to being precisely defined. Even the 5-7-5 element isn't 100% required. But these are a good start.)

1. A haiku includes some reference to nature. Typically this is a reference to the seasons, the weather, flowers, the sun, the moon, or the stars.

2. Each line of a haiku expresses a different concept from the others, though those concepts can build upon one another.

3. Either at the beginning of line 2 or line 3, there is an "ah-hah!" moment, where the reader realizes that the poem isn't about quite what he thought, or isn't going quite where he expected.

Here is a poor offering of a Lusternian haiku, by way of example:

Mother Moon rises;
Abeytu tends his moon fruit.
Shall we rage this night?

Oh.

That explains it then.

Ah hem.

Sweet smell of green grass.

Cutting like a sharpen'd blade,

Yet tickles bare feet.

Yes, and Haikus are not meant to continue on in sentence like form from line to line. Each line must exist on its own.

Awesome, so I AM allowed to do that in Senryu. I thought I was cheating. Eat that, Jack!

Well, poetry is not known for its rigidity of rules. But when you just write a sentence with 17 syllables on three lines, it can be argued that's not even a senryu, though that's what most "haiku" are.

"A prose writer gets tired of writing prose, and wants to be a poet. So he begins every line with a capital letter, and keeps on writing prose." - Samuel McChord Crothers

Senryu (Male Elfen).
He is 19 years old, having been born on the 22nd of Klangiary, 95 years after
the Coming of Estarra.
He is unranked in Lusternia.
He is an extremely credible character.
He is a Vagrant in the Fellowship of Explorers
He is surrounded by the Grace of Innocence.
He is considered to be approximately 0% of your might.
He is not currently active in any family.

O_o

Heh, that is funny.
I wonder if he knew that
or was just random.

No, I won't eat that.
However, I will eat you.
Preferably fried.