means To sanction is either to officially approve and authorize something, or to penalize someone (often a nation) for breaking a rule — the same word pulling in opposite directions.

from From Latin 'sanctio,' a binding decree or law, rooted in 'sancire,' to make sacred or inviolable — the same source that gives us 'sacred' and 'saint.' Originally a sanction was the part of a law that made it stick: the penalty attached to breaking it. From there the word drifted two ways — toward the authority that backs a rule (hence 'approval') and toward the punishment that enforces it. Both senses are simply the law showing its teeth and its seal at once.