Interestingly, the etymology (see below) of the word 'contract' shows that it comes from the Latin 'contractus' the past participle of the verb 'contrahere' to draw together.
Contract, noun, with the emphasis on the first syllable, means :
a voluntary arrangement between two or more parties that is enforceable by law as a binding legal agreement.
But, notably, when we use the verb form, regarding contracts, we emphasise the second syllable 'contract into the NHS scheme'. At least, that is the BrE emphasis.
Contract, the verb, emphasising the second syllable, as well as 'shrink', also means :
to draw together 'contract one's brow' or to catch a disease 'contract pneumonia'.
Shakespeare, who retired from writing in 1613, uses the word 26 times in his plays, (Shakespeare Concordance), mostly relating the noun 'contract' and the verb 'contract' to marriage, or, more specifically, to engagement to marry, underlining the view in olden times that an engagement was binding and one could be sued for withdrawing from it.
But he also uses the verb, in one place, in the other sense of 'drawing together' - 'contract his brow'.
The KJV Authorised Version of 1611 has chosen not to follow Shakespeare and never uses the word 'contract' in any sense, preferring 'covenant', not just in theological contexts but in all agreements, whatever the kind.
Modern uses of 'contract', 'agreement' and 'covenant' show a massive preference against 'covenant' and parity between 'agreement' and 'contract'; but the ngram does not, of course, differentiate between the meanings of the word 'contract'.
ETYMOLOGY - etymonline
early 14c., from Old French contract (Modern French contrat), from Latin contractus "a contract, agreement," from past participle of contrahere "to draw together," metaphorically, "to make a bargain," from com- "together" (see com-) + trahere "to draw" (see tract (n.1)). U.S. underworld sense of "arrangement to kill someone" first recorded 1940.
late 14c., "make narrow, draw together;" early 15c. "make an agreement;" from Middle French contracter, from Latin contractus, past participle of contrahere "to draw together, combine, make an agreement" (see contract (n.)). Related: Contracted; contracting.