an arrow that is shot from a crossbow; has a head with four edges
an angry dispute; "they had a quarrel"; "they had words"
have a disagreement over something; "We quarreled over the question as to who discovered America"; "These two fellows are always scrapping over something"
tending to or capable of propelling; "propellant fuel for submarines"; "the faster a jet plane goes the greater its propulsive efficiency"; "universities...the seats of propulsive thought"
a belief that can guide behavior; "the architect has a theory that more is less"; "they killed him on the theory that dead men tell no tales"
a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena; "theories can incorporate facts and laws and tested hypotheses"; "true in fact and theory"