jell 
(jĕl)
(jĕl)v. jelled, jell·ing, jells
v.intr.
1. To become firm or gelatinous; congeal.
2. To take shape or become clear; crystallize: A plan of action finally jelled in my mind.
v.tr.
1. To cause to become firm or gelatinous: used pectin to jell the jam.
2. To cause to take shape; make clear and definite; crystallize.
[Probably back-formation from JELLY.]