Word Study
coöperate
CIDE DICTIONARY
coöperate, v. i. [L. coöperatus, p. p. of coöperari to coöperate; co + operari to work, opus work. See Operate.].
To act or operate jointly with another or others; to concur in action, effort, or effect. [1913 Webster]
"Whate'er coöperates to the common mirth." [1913 Webster]
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