To move in small, quick movements from side to side or up and down, or to make something move that way. Your toes wiggle inside your shoes; a puppy wiggles when it is excited; you wiggle a loose tooth with your finger; you wiggle a key in a stiff lock to get it to turn. The movement is small, repeated, and usually a bit playful — that playfulness is a real part of the word, which is why adults use it a lot with children and pets and less in serious writing. It is also a noun: 'give it a wiggle'. Compare its neighbours: 'wriggle' is a whole body twisting to get through or get free (a worm, a child escaping a hug); 'jiggle' is more up-and-down shaking; 'squirm' is uncomfortable twisting. There is one very useful set phrase in business English: 'wiggle room', meaning a little space to change your mind, your price, or your plan.