What is the exact meaning of the word "appropriate" in this sentence, "The president asked Congress to provide $400 million for economic and military aid to Greece and Turkey, and the money was appropriated."?
One of the meanings of 'appropriate', when used as a verb, is 'to take'. For example, criminals in Britain may now have their ill-gotten property 'appropriated' by the authorities. In your example, Congress 'took' the money from a particular government fund to pay for what the President had asked. As RJA says above, it also implies that the money was 'set aside'.
appropriated, condemned, confiscate, confiscated, seized, taken_over
taken without permission or consent especially by public authority; "the condemned land was used for a highway cloverleaf"; "the confiscated liquor was poured down the drain"