Here's a riddle: When would a dictionary customized to respect trademarks not include the word customize? The answer: when that dictionary was published between 1932 and 1961. While we're satisfied our answer is accurate, it isn't especially satisfying, so we'll alter our response to include a more complete explanation.

Although the word customize had appeared in print as long ago as 1923 (it was originally used to mean "to make (goods) so as to resemble custom-made clothes"), in 1932 the Hickey-Freeman Clothing Company registered customize as a trademark. That company applied its word to a host of men's clothing (from frock garments to knickers) and the legally reserved customize was no longer permitted to be used without express permission from Hickey-Freeman. (来源：专业英语学习网站 http://www.EnglishCN.com)

But then, as sometimes happens, use of the word customize became customary among the public; that is to say, usage spread (or the company licensed to regulate its use no longer cared to do so), and the trademark protection was lost.

So, by 1961, when Webster's Third New International Dictionary was going to press, customize was once again included. Its definition? The same as it is today: "to build, fit, or alter according to individual specifications." (来源：英语麦当劳 http://www.EnglishCN.com)