LETTER BANK XXVIII

The key word represented as EIGHT is a letter bank for the key word represented as TWELVE. That is, only the letters in key word EIGHT, repeated as necessary, may be used to form key word TWELVE. The two key words do indeed have twelve and eight letters, respectively.

Patricia raced atop her horse.
   The dust blew in her eyes.
That TWELVE became an EIGHT,
   But still her goal remained the prize.

HINT:
What's a 12-letter word for horsewoman?

Answer:

That EQUESTRIENNE became a SQUINTER