What is a cost unit in cost accounting?

Cost unit is a unit of production, service or time or combination of these, in relation to which costs may be ascertained or expressed.

Ex:

Toy making:

Batch costing, unit of cost: per batch

(ex: $500 per batch)

Advertising:

Job Costing, unit of cost: per Job

Hospital:

Operating costing, unit of cost: per patient day