atom ,
n :
(now historical) The smallest medieval unit of time, equal to fifteen ninety-fourths of a second. [from 10th c.] (history of science) A hypothetical particle posited by Greek philosophers as an ultimate and indivisible component of matter. [from 15th c.] (chemistry, physics) The smallest possible amount of matter which still retains its identity as a chemical element, now known to consist of a nucleus surrounded by electrons. [from 16th c.] (now generally regarded figuratively) The smallest, indivisible constituent part or unit of something. [from 17th c.] A mote of dust in a sunbeam. [from 16th c.] A very small amount (of something immaterial); a whit. [from 17th c.] (computing, programming, Lisp) An individual number or symbol, as opposed to a list; a scalar value. (mathematics) A non-zero member of a Boolean algebra that is not a union of any other elements. [from 20th c.] The DC Comics title Justice League of America made its debut this month in 1960.
