To push and rub someone's hair about so it ends up untidy. The classic picture is an adult ruffling a child's hair with one hand — a warm, affectionate gesture — and that gentleness is usually part of the word: you tousle a child's hair, or a lover's; you do not tousle an enemy's. Wind and sleep can do it too, with no hand involved: the sea breeze tousled her hair. It is a soft, slightly literary word, much more common in novels and in writing about films or fashion than in daily conversation, where most people just say mess up or ruffle. You will actually meet the past participle tousled far more often than the plain verb. Rhymes with the first part of 'thousand' — "TOW-zul".

把（頭髮）弄亂、揉亂（常是寵溺地揉小孩的頭）