quar·ter·ly 
(kwôrtər-lē)
(kwôrtər-lē)adj.
1. Made up of four parts.
2. Being one of four parts.
3. Occurring or appearing at three-month intervals: a quarterly magazine; a quarterly payment.
4. Heraldry Having four sections. Used of a shield.
n. pl. quar·ter·lies
1. A publication issued regularly every three months.
2. An examination given regularly every three months in some colleges.
adv.
In or by quarters.