1. Busy, diligent, industrious imply active or earnest effort to accomplish something, or a habitual attitude of such earnestness. Busy means actively employed, temporarily or habitually: a busy official. Diligent suggests earnest and constant effort or application, and usually connotes fondness for, or enjoyment of, what one is doing: a diligent student. Industrious often implies a habitual characteristic of steady and zealous application, often with a definite goal: an industrious clerk working for promotion.

Did you mean bushing?