3. Begin, commence, initiate, start (when followed by noun or gerund) refer to setting into motion or progress something that continues for some time. Begin is the common term: to begin knitting a sweater. Commence is a more formal word, often suggesting a more prolonged or elaborate beginning: to commence proceedings in court. Initiate implies an active and often ingenious first act in a new field: to initiate a new procedure. Start means to make a first move or to set out on a course of action: to start paving a street. 4. institute, inaugurate, initiate.