In language study, false friends are words that are similar to a word in a foreign language, but have a more or less different meaning. To complicate things, as words can have multiple meanings, sometimes only one of the meanings corresponds, and the others don't. An example is "to pretend," which corresponds to the Italian "pretendere" only in its secondary meaning "to expect, demand." The usual meaning of "to pretend" is "fingere" in Italian. In turn "to demand" is itself a false friend, not corresponding to "domandare," which means "to ask." "To demand" is rendered by "esigere."
Some common examples. English "actually" and Italian "attualmente," meaning respectively "in reality" and "currently." English "eventually" and Italian "eventualmente," meaning "sooner or later" and "may happen or then again may not, who knows". I suspect that the latter example reflects cultural differences between the English-speaking world and Italians. Some can have undesired consequences, such as hilarity. English "preservative" and Italian "preservativo" stand for "substance to preserve products" and "condom".
Here is a list (by no means exhaustive) of these pesky critters.
