Introductory post:

Okay, now let's do a little jump down to Greece, with thanks to Lewis Turco and his Book of Forms.

Alcaics is a accentual-syllabic Greek quatrain (four-line) stanza form. 

Lines 1 & 2 are eleven syllables each, made up of:
An acephalous iamb. This means the word is 'headless' - merely a fancy way of saying that it is the accented syllable that is left - the unaccented first syllable has been dropped.  This 'headless' one is followed by two trochees and two dactyls, in that order.  (TA-ta  TA-ta, TA-ta-ta  TA-ta-ta)

Line 3 is nine syllables, made up of an acephalous iamb followed by four trochees.  (TA-ta  x 4)

Line 4 is 10 syllables: two dactyls followed by two trochees. (TA-ta-ta TA-ta-ta, TA-ta TA-ta)

There is no limit to the number of stanzas and no requirement to rhyme.

Diagrammed it would appear:

' | '~ | '~ | ' ~ ~ | ' ~ ~
x  xx  xx  xxx  xxx

' | '~ | '~ | ' ~ ~ | ' ~ ~
x  xx  xx  xxx  xxx

' | ' ~ |  ' ~ | ' ~ | ' ~
x  xx  xx  xx  xx

' ~ ~ | ' ~ ~ | ' ~ | ' ~
xxx  xxx  xx  xx

A small example, thinking on my cat this morning:


O feline huntress stalking the tuna-can,
O rubbing dancer twining the opener,
I, bending downward, receive caress,
Purringly, eagerly, weakness confess.


The Legend of Crickhollow

Nine hessian horse-thieves cannonball catering
All seemly creatures speedily scattering
Jack lantern kernels, thinly leering
Crickhollow Fredegar, legend living.
- Beruthiel

Speaking of headless things...

Lurtz, prideful, over-confident pursuer
So certain, thinking muscular savagery
All! Bearing weapons crudely fashioned,
Skewering - Suddenly ker-plop! Headless.
- Primula

Shire children at play in open fields, here, there
Among the cornstalks scarecrow stands tempting sweet
Ah, fresh pumpkinhead placed yesterday
It's sunwarmed odor them commands - Eating!
- Beruthiel

Dark Companion

O shadow, my shade, on my heels following
Race sunlight shyly, in the dark you escape
I, turning, spurning, casting, flinging
Forever fleeing—you cling like a cape.