The Collaborative International Dictionary of English v.0.48:

Oop \Oop\ ([=oo]p), v. t. [Etymol. uncertain.]
   To bind with a thread or cord; to join; to unite. [Scot.]
   --Jamieson.
   [1913 Webster] Oopack

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

OOP
       Object Orientated Programming (OOP)


The Free On-line Dictionary of Computing (30 December 2018):

object-oriented programming
object-oriented language
object-oriented programming language
OOP
OOPL

    (OOP) The use of a class of programming
   languages and techniques based on the concept of an "object"
   which is a data structure (abstract data type) encapsulated
   with a set of routines, called "methods", which operate on
   the data.  Operations on the data can __only__ be performed via
   these methods, which are common to all objects that are
   instances of a particular "class".  Thus the interface to
   objects is well defined, and allows the code implementing the
   methods to be changed so long as the interface remains the
   same.

   Each class is a separate module and has a position in a
   "class hierarchy".  Methods or code in one class can be
   passed down the hierarchy to a subclass or inherited from a
   superclass.  This is called "inheritance".

   A procedure call is described as invoking a method on an
   object (which effectively becomes the procedure's first
   argument), and may optionally include other arguments.  The
   method name is looked up in the object's class to find out how
   to perform that operation on the given object.  If the method
   is not defined for the object's class, it is looked for in its
   superclass and so on up the class hierarchy until it is found
   or there is no higher superclass.

   OOP started with SIMULA-67 around 1970 and became
   all-pervasive with the advent of C++, and later Java.
   Another popular object-oriented programming language (OOPL) is
   Smalltalk, a seminal example from Xerox's Palo Alto
   Research Center (PARC).  Others include Ada, Object
   Pascal, Objective C, DRAGOON, BETA, Emerald, POOL,
   Eiffel, Self, Oblog, ESP, LOOPS, POLKA, and
   Python.  Other languages, such as Perl and VB, permit,
   but do not enforce OOP.

   FAQ (http://iamwww.unibe.ch/~scg/OOinfo/FAQ/).
   (http://zgdv.igd.fhg.de/papers/se/oop/).
   (http://cuiwww.unige.ch/Chloe/OOinfo).

   Usenet newsgroup: news:comp.object.

   (2001-10-11)