The Collaborative International Dictionary of English v.0.48:

Coercion \Co*er"cion\, n. [L. coercio, fr. coercere. See
   Coerce.]
   1. The act or process of coercing.
      [1913 Webster]

   2. (Law) The application to another of either physical or
      moral force. When the force is physical, and cannot be
      resisted, then the act produced by it is a nullity, so far
      as concerns the party coerced. When the force is moral,
      then the act, though voidable, is imputable to the party
      doing it, unless he be so paralyzed by terror as to act
      convulsively. At the same time coercion is not negatived
      by the fact of submission under force. "Coactus volui" (I
      consented under compulsion) is the condition of mind
      which, when there is volition forced by coercion, annuls
      the result of such coercion. --Wharton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

coercion
    n 1: the act of compelling by force of authority
    2: using force to cause something to occur; "though pressed into
       rugby under compulsion I began to enjoy the game"; "they
       didn't have to use coercion" [syn: compulsion, coercion]

The Free On-line Dictionary of Computing (19 January 2023):

implicit type conversion
coercion

    (Or "coercion") The abilty of some compilers
   to automatically insert type conversion functions where an
   expression of one type is used in a context where another type
   is expected.

   A common example is coercion of integers to reals so that
   an expression like sin(1) is compiled as sin(integerToReal(1))
   where sin is of type Real -> Real.

   A coercion is usually performed automatically by the compiler
   whereas a cast is an explicit type conversion inserted by
   the programmer.

   See also subtype.

   (1997-07-28)