acceleration of a chemical reaction induced the presence of material that is chemically unchanged at the end of the reaction; "of the top 50 commodity chemicals, 30 are created directly by catalysis and another 6 are made from raw materials that are catalytically produced"
a tentative theory about the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena; "a scientific hypothesis that survives experimental testing becomes a scientific theory"; "he proposed a fresh theory of alkalis that later was accepted in chemical practices"
a proposal intended to explain certain facts or observations
a general course along which something has a tendency to develop; "I couldn't follow the direction of his thoughts"; "his ideals determined the direction of his career"; "they proposed a new direction for the firm"
a message describing how something is to be done; "he gave directions faster than she could follow them"
a line leading to a place or point; "he looked the other direction"; "didn't know the way home"
the spatial relation between something and the course along which it points or moves; "he checked the direction and velocity of the wind"