1) Marginal 2) Progressive 1) Progressive 
• (a.) Pertaining to, or resulting from, the process of growth; as, the incremental lines in the dentine of teeth.
[Adjective] Increasing something by small amounts.
refers to an output that is measured in known increments from a known reference point; e.g., a step motor provides incremental motion based on an initial position and an incremental encoder provides incremental feedback information based on a known zero point.
An increase in product sales volume attributed to a special promotion or merchandising plan. 
In`cre·men'tal adjective (Biol.) Pertaining to, or resulting from, the process of growth; as, the incremental lines in the dentine of teeth. 
[adj] - increasing gradually by regular degrees or additions
Incremental sales - The additional sales of a product occurring directly as a result of a specific activity (e.g. sales promotion).
adjective increasing gradually by regular degrees or additions; `lecturers enjoy...steady incremental growth in salary`
increasing gradually by regular degrees or additions[Inspiring words] increasing gradually by regular degrees or additions[ACT vocabulary] increasing gradually by regular degrees or additions