Definition of "constrain"

constrain

/kənˈstɹeɪn/

verb
third-person singular simple present constrains, present participle constraining, simple past and past participle constrained
1. (transitive) To force physically, by strong persuasion or pressuring; to compel; to oblige.
2. (transitive) To keep within close bounds; to confine.
  Quotations
  But it's not just Castlefield Corridor capacity that constrains services. All the junctions on the lines feeding into the corridor are flat, so they create conflict points as trains pass.
  2020 January 2, Philip Haigh, “Is there relief to congestion along Castlefield Corridor?”, in Rail, page 23
3. (transitive) To reduce a result in response to limited resources.