Lead screw

Lead Lead, n. 1. The act of leading or conducting; guidance; direction; as, to take the lead; to be under the lead of another. [1913 Webster]

At the time I speak of, and having a momentary lead, . . . I am sure I did my country important service. --Burke. [1913 Webster]

2. Precedence; advance position; also, the measure of precedence; as, the white horse had the lead; a lead of a boat's length, or of half a second. [1913 Webster]

3. (Cards & Dominoes) The act or right of playing first in a game or round; the card suit, or piece, so played; as, your partner has the lead. [1913 Webster]

4. An open way in an ice field. --Kane. [1913 Webster]

5. (Mining) A lode. [1913 Webster]

6. (Naut.) The course of a rope from end to end. [1913 Webster]

7. (Steam Engine) The width of port opening which is uncovered by the valve, for the admission or release of steam, at the instant when the piston is at end of its stroke. [1913 Webster]

Note: When used alone it means outside lead, or lead for the admission of steam. Inside lead refers to the release or exhaust. [1913 Webster]

8. (Civil Engineering) the distance of haul, as from a cutting to an embankment. [1913 Webster]

9. (Horology) The action of a tooth, as a tooth of a wheel, in impelling another tooth or a pallet. --Saunier. [1913 Webster]

10. (Music.) (a) The announcement by one voice part of a theme to be repeated by the other parts. (b) A mark or a short passage in one voice part, as of a canon, serving as a cue for the entrance of others. [Webster 1913 Suppl.]

11. In an internal-combustion engine, the distance, measured in actual length of piston stroke or the corresponding angular displacement of the crank, of the piston from the end of the compression stroke when ignition takes place; -- called in full

{lead of the ignition}. When ignition takes place during the working stroke the corresponding distance from the commencement of the stroke is called

{negative lead}. [Webster 1913 Suppl.]

12. (Mach.) The excess above a right angle in the angle between two consecutive cranks, as of a compound engine, on the same shaft. [Webster 1913 Suppl.]

13. (Mach.) In spiral screw threads, worm wheels, or the like, the amount of advance of any point in the spiral for a complete turn. [Webster 1913 Suppl.]

14. (Elec.) (a) The angle between the line joining the brushes of a continuous-current dynamo and the diameter symmetrical between the poles. (b) The advance of the current phase in an alternating circuit beyond that of the electromotive force producing it. [Webster 1913 Suppl.]

15. (Theat.) A role for a leading man or leading woman; also, one who plays such a role. [Webster 1913 Suppl.]

16. The first story in a newspaper or broadcast news program. [PJC]

17. an electrical conductor, typically as an insulated wire or cable, connecting an electrical device to another device or to a power source, such as a conductor conveying electricity from a dynamo. [PJC]

18. (Baseball) the distance a runner on base advances from one base toward the next before the pitch; as, the long lead he usually takes tends to distract the pitchers. [PJC]

{Lead angle} (Steam Engine), the angle which the crank maker with the line of centers, in approaching it, at the instant when the valve opens to admit steam.

{Lead screw} (Mach.), the main longitudinal screw of a lathe, which gives the feed motion to the carriage. [1913 Webster]