Adjective

(en adjective)

Required; obligatory; mandatory.

* 1827 , A. D. Jr., Edinburgh Medical and Surgical Journal , A. and C. Black, page 212:

They are entirely private concerns, established by individual teachers, and attendance upon them is no more compulsory than attendance on our dispensaries.

* 1996 , (Ugo Pagano), Democracy and Efficiency in the Economic Enterprise , page 73:

Some might agree that membership in the firm is perhaps more compulsory than membership in a municipality, but balk at applying the analogy to the nation.

* {{quote-magazine, date=2013-07-19, author=(Peter Wilby)

, volume=189, issue=6, page=30, magazine=(The Guardian Weekly) , title= Finland spreads word on schools , passage=Imagine a country where children do nothing but play until they start compulsory schooling at age seven. Then, without exception, they attend comprehensives until the age of 16. Charging school fees is illegal, and so is sorting pupils into ability groups by streaming or setting.}}

Having the power of compulsion; constraining.

Adjective

(en adjective)

Acting as a complement.

*

Using the terminology we intro-
duced earlier, we might then say that black and white squares are in comple-
mentary distribution on a chess-board. By this we mean two things: firstly,
black squares and white squares occupy different positions on the board: and
secondly, the black and white squares complement each other in the sense that
the black squares together with the white squares comprise the total set of 64
squares found on the board (i.e. there is no square on the board which is not
either black or white).

(genetics) Of the specific pairings of the bases in DNA and RNA.

(physics) Pertaining to pairs of properties in quantum mechanics that are inversely related to each other, such as speed and position, or energy and time. (See also Heisenberg uncertainty principle.)