Etymology: Middle English, plumb line, from Anglo-French livel, from Vulgar Latin *libellum, alteration of Latin libella, from diminutive of libra weight, balance
Date: 14th century
1. a device for establishing a horizontal line or plane by means of a bubble in a liquid that shows adjustment to the horizontal by movement to the center of a slightly bowed glass tube
2. a measurement of the difference of altitude of two points by means of a level
3. horizontal condition; especially equilibrium of a fluid marked by a horizontal surface of even altitude <water seeks its own level> 4. a. an approximately horizontal line or surface taken as an index of altitude b. a practically horizontal surface or area (as of land) 5. a position in a scale or rank (as of achievement, significance, or value) <funded at the national level> <the job appeals to me on many levels> 6. a. a line or surface that cuts perpendicularly all plumb lines that it meets and hence would everywhere coincide with a surface of still water b. the plane of the horizon or a line in it 7. a horizontal passage in a mine intended for regular working and transportation 8. a concentration of a constituent especially of a body fluid (as blood) 9. the magnitude of a quantity considered in relation to an arbitrary reference value; broadly magnitude, intensity <a high level of hostility> II. verb (-eled or -elled; -eling or levelling) Date: 15th century transitive verb 1. to make (a line or surface) horizontal ; make flat or level <level a field> <level off a house lot> 2. a. to bring to a horizontal aiming position b. aim, direct <leveled a charge of fraud> 3. to bring to a common level or plane ; equalize <love levels all ranks — W. S. Gilbert> 4. a. to lay level with or as if with the ground ; raze b. to knock down <leveled him with one punch> 5. to make (as color) even or uniform 6. to find the heights of different points in (a piece of land) especially with a surveyor's level intransitive verb 1. to attain or come to a level <the plane leveled off at 10,000 feet> 2. to aim a gun or other weapon horizontally 3. to bring persons or things to a level 4. to deal frankly and openly III. adjective Date: 15th century 1. a. having no part higher than another ; conforming to the curvature of the liquid parts of the earth's surface b. parallel with the plane of the horizon ; horizontal 2. a. even or unvarying in height b. equal in advantage, progression, or standing c. proceeding monotonously or uneventfully d. (1) steady, unwavering <gave him a level look> (2) calm, unexcited <spoke in level tones> 3. reasonable, balanced <arrive at a justly proportional and level judgment on this affair — Sir Winston Churchill> 4. distributed evenly <level stress> 5. being a surface perpendicular to all lines of force in a field of force ; equipotential 6. suited to a particular rank or plane of ability or achievement <top-level thinking> 7. of or relating to the spreading out of a cost or charge in even payments over a period of time • levelly adverb • levelness noun Synonyms: level, flat, plane, even, smooth mean having a surface without bends, curves, or irregularities. level applies to a horizontal surface that lies on a line parallel with the horizon <the vast prairies are nearly level>. flat applies to a surface devoid of noticeable curvatures, prominences, or depressions <the work surface must be flat>. plane applies to any real or imaginary flat surface in which a straight line between any two points on it lies wholly within that surface <the plane sides of a crystal>. even applies to a surface that is noticeably flat or level or to a line that is observably straight <trim the hedge so it is even>. smooth applies especially to a polished surface free of irregularities <a smooth skating rink>.
New Collegiate Dictionary. 2001.