slate

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A fine-grained metamorphic rock that splits into thin, smooth-surfaced layers.
• noun A piece of this rock cut for use as roofing or surfacing material or as a writing surface.
• noun A writing tablet made of a similar material.
• noun A record of past performance or activity.
• noun A list of the candidates of a political party running for various offices.
• noun A dark or bluish gray to dark bluish or dark purplish gray.
• adjective Made of a fine-grained metamorphic rock.
• adjective Of the color slate.
• transitive verb To cover (a roof, for example) with slate.
• transitive verb To put on a list of candidates.
• transitive verb To schedule or designate.

from The Century Dictionary.

• noun A thin, flat stone or piece of stone; a thin plate or flake. See slat, 1.
• noun Especially A piece or plate of the stone hence called slate. (See def. 3.)
• noun A rock the most striking characteristic of which is its fissile structure, or capability of being easily split or cleft into thin plates of nearly uniform thickness and smooth surfaces.
• noun A preliminary list of candidates prepared by party managers for acceptance by a nominating caucus or convention: so called as being written down, as it were on a slate, and altered or erased like a school-boy's writing.
• noun (which see, under chalk).
• Of the color of slate; slate-colored; of a dark, slightly bluish-gray color of medium luminosity.
• To bait; set a dog loose at.
• To haul over the coals; take to task harshly or rudely; berate; abuse; scold; hold up to ridicule; criticize severely: as, the work was slated in the reviews.
• To cover with slate or plates of stone: as, to slate a roof.
• To enter as on a slate; suggest or propose as a candidate by entering the name on the slate or ticket: as, A. B. is already slated for the mayoralty. See I., 4.
• In tanning, to cleanse from hairs, etc., with a slater. See slater, 3.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Min.) An argillaceous rock which readily splits into thin plates; argillite; argillaceous schist.
• noun Any rock or stone having a slaty structure.
• noun A prepared piece of such stone.
• noun A thin, flat piece, for roofing or covering houses, etc.
• noun A tablet for writing upon.
• noun An artificial material, resembling slate, and used for the above purposes.
• noun obsolete A thin plate of any material; a flake.
• noun (Politics), Cant, U.S. A list of candidates, prepared for nomination or for election; a list of candidates, or a programme of action, devised beforehand.
• noun (Min.) a kind of slate of a greenish gray color, which absorbs water rapidly, and adheres to the tongue; whence the name.
• noun (Min.) a kind of slate containing sulphate of alumina, -- used in the manufacture of alum.
• noun (Min.) a soft species of sectile clay slate, impregnated with bitumen.
• noun (Min.) a slaty rock, consisting essentially of hornblende and feldspar, useful for flagging on account of its toughness.
• noun a mattock with an ax end, used in shaping slates for roofs, and making holes in them for the nails.
• noun (Geol.) an indurated clay, forming one of the alternating beds of the coal measures, consisting of an infusible compound of alumina and silica, and often used for making fire bricks.
• noun a globe the surface of which is made of an artificial slatelike material.
• noun a pencil of slate, or of soapstone, used for writing on a slate.
• noun (Min.) rocks which split into thin laminæ, not necessarily parallel to the stratification; foliated rocks.
• noun (Min.) a variety of calcite of silvery white luster and of a slaty structure.
• noun a plate of translucent material, as ground glass, upon which a copy of a picture, placed beneath it, can be made by tracing.
• transitive verb Prov. Eng. & Scot. To set a dog upon; to bait; to slat. See 2d slat, 3.
• transitive verb To cover with slate, or with a substance resembling slate
• transitive verb Polit. Cant To register (as on a slate and subject to revision), for an appointment.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun uncountable A fine-grained homogeneous sedimentary rock composed of clay or volcanic ash which has been metamorphosed so that it cleaves easily into thin layers.
• noun uncountable The bluish-grey colour of most slate.
• noun countable A sheet of slate for writing on with chalk.