1. Something put into a system or expended in its operation to achieve output or a result, especially:
   1. Energy, work, or power used to drive a machine.
   2. Current, electromotive force, or power supplied to an electric circuit, network, or device.
   3. Computer Science Information put into a communications system for transmission or into a computer system for processing.
   4. Computer Science A position, terminal, or station at which input enters a system.
   5. Any of the items, including materials, equipment, and funds, required for production.
   6. The act of putting in; infusion: a steady input of fuel.
   7. An amount put in.
   8. Contribution of information or a comment or viewpoint: a discussion with input from all members of the group.
   9. Information in general.
2. 1. The act of putting in; infusion: a steady input of fuel.
   2. An amount put in.
   3. Contribution of information or a comment or viewpoint: a discussion with input from all members of the group.
   4. Information in general.
3. Usage Problem
   1. Contribution of information or a comment or viewpoint: a discussion with input from all members of the group.
   2. Information in general.

Usage Note: The noun input has been used as a technical term for about a century in fields such as physics and electrical engineering, but its recent popularity grows out of its use in computer science, where it refers to data or signals entered into a system for processing or transmission. In general discourse input is now widely used to refer to the transmission of information and opinion, as in The report questioned whether a President thus shielded had access to a sufficiently varied input to have a realistic picture of the nation or The nominee herself had no input on housing policy. In this last sentence the meaning of the term is uncertain: it may mean either that the nominee provided no opinions to the policymakers or that she received no information about housing policy. This vagueness in the nontechnical use of input may be one reason that some critics have objected to it (including, in an earlier survey, a majority of the Usage Panel). Though the usage is well established, care should be taken not to use the word merely as a way to imply an unwarranted scientific precision.