いい悪いは別にしてカプセル化、継承、ポリモーフィズムの3原則が広まったのもBoochの本によるもの
Boochの定義は「継承を使わずADTを使うだけではオブジェクト指向とは言わない」と明記してるところに価値がある

あとは英語版のWikipediaの定義は平易でいいと思う
(また英語で悪いが日本語版の記述は駄目なので)

Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects",
which can contain data, in the form of fields (often known as attributes or properties),
and code, in the form of procedures (often known as methods).
A feature of objects is an object's procedures that can access and often modify the data fields of the object
with which they are associated (objects have a notion of "this" or "self").
In OOP, computer programs are designed by making them out of objects that interact with one another.