Look at the dictionary entry that follows this sentence. What is the meaning of the word "constrains as it is used in the sentence?

"Such has been the patient sufferance of these Colonies,
and such is now the necessity which constrains them to
alter their former Systems of Government."

Thomas Jefferson, Declaration of Independence, printed
by John Dunlap, July 4, 1776, Records of the Continental
and Confederation, Congresses and the Constitutional
Convention, 1774-1789, Record Group 360, National
Archives, http://www. ourdocuments. gov/doc. php?doc=2.

con / strain (verb)

1 a: to force by imposing limitations or restrictions
b: to limit the motion of someone or something in a
particular fashion
2: to fasten with bonds: confine; LIMIT
3: to hold back with force

A. To force by imposing limitations or restrictions

B. To limit the motion of someone or something in a particular
fashion

C. To hold back with force

D. To fasten with bonds

A because of the context used constrain is being held back with restrictions instead of force

cassius, casca, and their allies plant false documents to manipulate brutus to join their cause to remove caesar. after doing so, they visit brutus at night in his home to persuade him of their views. there they plan caesar's death. brutus is troubled but refuses to confide in his devoted wife, portia. on 15 march, caesar's wife, calpurnia, urges him not to go to the senate. she has had visionary dreams and fears the portents of the overnight storms.

the tone of the passage is sympathetic to the forbidden love of romeo and juliet. the nurse plays a significant role in the play. she is responsible for making their meeting again possible. additionally, there is a sense of warning in the choice of words of the nurse. she seems to be authoritative when she calls romeo "scurvy knave", and at the same time the fact that she addresses to him as "sir" reflects respect. the nurse is "vexed", this word describes her confused state of mind. on the one hand, she finds romeo a fine and eloquent man, but on the other, it is thought that man's nature forces men to try to trick women.