- closed differential field
- closed differential form
- closed differential relation
- closed disk
- closed domain
- closed edge sequence
- closed edge train
- closed element
- closed embedding
- closed equivalence relation
- closed extension
- closed family of sets
- closed field
- closed filter
- closed form
- closed-form number
- closed-form solution
- closed formula
- closed function
- closed geodesic
- closed graph
- closed-graph mapping
- closed-graph theorem
- closed grill
- closed ground field