Tacit refers to something that is implied by actions or statements. A tacit agreement, for instance, is one where either the offer or the acceptance are to be inferred from a particular conduct. It comes from the Latin tacitus, which means silent.
This was a tacit acknowledgement that recent money-market interventions had failed to cap the unusually high rates banks were charging each other for one-month and three-month loans. (The Economist)
By the time the Administration gave its tacit assent to Iranian arms shipments into Bosnia and Herzegovina, weapons already were flowing from Teheran to the Government in Sarajevo, Anthony Lake, President Clinton’s national security adviser, said today. (NY Times)