any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter
to move in a twisting or contorted motion, (especially when struggling); "The prisoner writhed in discomfort"; "The child tried to wriggle free from his aunt's embrace"
a remote or indirect consequence of some action; "his declaration had unforeseen repercussions"; "reverberations of the market crash were felt years later"