noun

1. the science of correct reasoning; science which describes relationships among propositions in terms of implication, contradiction, contrariety, conversion, etc.
2. a book dealing with this science
3. correct reasoning; valid induction or deduction the lack of logic in his scheme
4. way of reasoning, whether correct or incorrect to use faulty logic
5. the system of principles underlying any art or science
6. necessary connection or outcome, as through the working of cause and effect the logic of events
7. the systematized interconnection of switching functions, circuits, or devices, as in electronic computers

Etymology: ME logike < OFr logique < L logica < Gr logikē (technē), logical (art) < logikos, of speaking or reasoning < logos, a word, reckoning, thought < legein, to speak, choose, read < IE base *le-, to gather > L legere, to collect, OE læce, leech