8. An unsound or worn-out horse, useful as a hack, and commonly of good
appearance. Ld. Lytton.
9. (Math.) A straight line in space with which a definite linear
magnitude termed the pitch is associated (cf. 5th Pitch, 10 (b)). It is
used to express the displacement of a rigid body, which may always be
made to consist of a rotation about an axis combined with a translation
parallel to that axis.
10. (Zoöl.) An amphipod crustacean; as, the skeleton screw (Caprella).
See Sand screw, under Sand.
Archimedes screw, Compound screw, Foot screw, etc. See under
Archimedes, Compound, Foot, etc. -- A screw loose, something out of
order, so that work is not done smoothly; as, there is a screw loose
somewhere. H. Martineau. -- Endless, or perpetual, screw, a screw used
to give motion to a toothed wheel by the action of its threads between
the teeth of the wheel; -- called also a worm. -- Lag screw. See under
Lag. -- Micrometer screw, a screw with fine threads, used for the
measurement of very small spaces. -- Right and left screw, a screw
having threads upon the opposite ends which wind in opposite
directions. -- Screw alley. See Shaft alley, under Shaft. -- Screw
bean. (Bot.) (a) The curious spirally coiled pod of a leguminous tree
(Prosopis pubescens) growing from Texas to California. It is used for
fodder, and ground into meal by the Indians. (b) The tree itself. Its
heavy hard wood is used for fuel, for fencing, and for railroad ties.
-- Screw bolt, a bolt having a screw thread on its shank, in
distinction from a key bolt. See 1st Bolt, 3. -- Screw box, a device,
resembling a die, for cutting the thread on a wooden screw. -- Screw
dock. See under Dock. -- Screw engine, a marine engine for driving a
screw propeller. -- Screw gear. See Spiral gear, under Spiral. -- Screw
jack. Same as Jackscrew. -- Screw key, a wrench for turning a screw or
nut; a spanner wrench. -- Screw machine. (a) One of a series of
machines employed in the manufacture of wood screws. (b) A machine tool
resembling a lathe, having a number of cutting tools that can be caused
to act on the work successively, for making screws and other turned
pieces from metal rods. -- Screw pine (Bot.), any plant of the
endogenous genus Pandanus, of which there are about fifty species,
natives of tropical lands from Africa to Polynesia; -- named from the
spiral arrangement of the pineapple-like leaves. -- Screw plate, a
device for cutting threads on small screws, consisting of a thin steel
plate having a series of perforations with internal screws forming
dies. -- Screw press, a press in which pressure is exerted by means of
a screw. -- Screw propeller, a screw or spiral bladed wheel, used in
the propulsion of steam vessels; also, a steam vessel propelled by a
screw. -- Screw shell (Zoöl.), a long, slender, spiral gastropod shell,
especially of the genus Turritella and allied genera. See Turritella.
-- Screw steamer, a steamship propelled by a screw. -- Screw thread,
the spiral rib which forms a screw. -- Screw stone (Paleon.), the
fossil stem of an encrinite. -- Screw tree (Bot.), any plant of the
genus Helicteres, consisting of about thirty species of tropical
shrubs, with simple leaves and spirally twisted, five-celled capsules;
-- also called twisted-horn, and twisty. -- Screw valve, a stop valve
which is opened or closed by a screw. -- Screw worm (Zoöl.), the larva
of an American fly (Compsomyia macellaria), allied to the blowflies,
which sometimes deposits its eggs in the nostrils, or about wounds, in
man and other animals, with fatal results. -- Screw wrench. (a) A
wrench for turning a screw. (b) A wrench with an adjustable jaw that is
moved by a screw. -- To put the screw, or screws, on, to use pressure
upon, as for the purpose of extortion; to coerce. -- To put under the
screw or screws, to subject to pressure; to force. -- Wood screw, a
metal screw with a sharp thread of coarse pitch, adapted to holding
fast in wood. See Illust. of Wood screw, under Wood.
Screw (?), v. t. [imp. & p. p. Screwed (?); p. pr. & vb. n. Screwing.]
1. To turn, as a screw; to apply a screw to; to press, fasten, or make
firm, by means of a screw or screws; as, to screw a lock on a door; to
screw a press.