an anatomical structure used as a point of origin in locating other anatomical structures (as in surgery) or as point from which measurements can be taken
a mark showing the boundary of a piece of land
an event marking a unique or important historical change of course or one on which important developments depend; "the agreement was a watershed in the history of both nations"
the position of a prominent or well-known object in a particular landscape; "the church steeple provided a convenient landmark"
some situation or event that is thought about; "he kept drifting off the topic"; "he had been thinking about the subject for several years"; "it is a matter for the police"
a subdivision of a written work; usually numbered and titled; "he read a chapter every night before falling asleep"
a series of related events forming an episode; "a chapter of disasters"
a local branch of some fraternity or association; "he joined the Atlanta chapter"
an ecclesiastical assembly of the monks in a monastery or even of the canons of a church
any distinct period in history or in a person's life; "the industrial revolution opened a new chapter in British history"; "the divorce was an ugly chapter in their relationship"
the choicest or most essential or most vital part of some idea or experience; "the gist of the prosecutor's argument"; "the heart and soul of the Republican Party"; "the nub of the story"
a single whole grain of a cereal; "a kernel of corn"
the inner and usually edible part of a seed or grain or nut or fruit stone; "black walnut kernels are difficult to get out of the shell"
a question raised for consideration or solution; "our homework consisted of ten problems to solve"
a state of difficulty that needs to be resolved; "she and her husband are having problems"; "it is always a job to contact him"; "urban problems such as traffic congestion and smog"
(cryogenics) the lowest temperature theoretically attainable (at which the kinetic energy of atoms and molecules is minimal); 0 Kelvin or -273.15 centigrade or -459.67 Fahrenheit
absolutely required and not to be used up or sacrificed
absolutely necessary; vitally necessary; "essential tools and materials"; "funds essential to the completion of the project"; "an indispensable worker"
being or relating to or containing the essence of a plant etc; "essential oil"
the fundamental assumptions from which something is begun or developed or calculated or explained; "the whole argument rested on a basis of conjecture"
the most important or necessary part of something; "the basis of this drink is orange juice"