1) By fits and starts 2) Infrequently 3) Randomly 4) Restlessly 5) Sporadically 6) Unequally 7) Unevenly 1) Having an irregular form 2) In an irregular manner 3) On an irregular basis 
• (adv.) In an irregular manner.
Ir·reg'u·lar·ly adverb In an irregular manner. 
[adv] - having an irregular form 2. [adv] - in an irregular manner 3. [adv] - in an irregular manner 4. [adv] - in an irregular manner
on an irregular basis adverb in an irregular manner; `her letters arrived irregularly`