Abcedarius is a rare variant spelling of abecedarius, a poem or passage arranged in alphabetical order. Often, each line or stanza begins with the next letter of the alphabet, from A to Z. Writers use the pattern as a formal constraint, and in some traditions it can also support acrostic effects or devotional structure.
See Abecedarian.
Example
A is the dawn that opens the day,
B is the bird rising away,
C is the creek in a silver line,
D is the dogwood's bloom in time.