In a book called Intellectuals and Society, A Study of Teachers in India by Kameshwar Choudhary (2004), there is a more thorough research about the origins of the term:
The term ‘intellectual’... came to the English language partly through French in which it is Intellectuel, the word used for the first time in French in 1265 as a noun signifying one who is concerned with knowledge or understanding.
According to The Oxford English Dictionary, the term intellectual signifies
a person possessing or supposed to possess superior powers of intellect.
It cites a number of examples of former use of the term. In 1652, for instance, Benlowes talked of
First race of Intellectuals.
In 1813, Byron said,
Canning is to be here, Frere and Sharpe, — perhaps Gifford... I wish I may be well enough to listen to these intellectuals.
In 1884, A.A. Watts referred to
The silent person who astonished Coleridge at a dinner of intellectuals.
On 30 November 1898 the Daily News reported,
Proceeding to refer to the so-called intellectuals of Constantinople, who were engaged in discussion while the Turks were taking possession of the city.
On 19 December 1903, the Saturday Review stated,
We are compelled to rank higher the mind of the average young man of fashion than the mind of the average “intellectual” _ at those literary tea-parties.
On 12 August 1960, the Times Literary Supplement mentioned,
The English have a great respect for brute facts; and the intellectual in politics often looks to them like a man busily engaged in brushing unpleasant facts under the carpet.
The same author then goes on to quote Raymond Williams, the Welsh writer:
Raymond Williams holds that the word ‘intellectual’ has been an ordinary objective, from the fourteenth century, for ‘intelligence’ in its most general sense. However, it became a noun to signify the faculties or processes of ‘intelligence’. According to him, the use of the word ‘intellectual’ as a noun to refer to a particular kind of person or a person doing a particular kind of work dates effectively from the first third of the nineteenth century though it had some isolated earlier instances. Moreover, he notes the application of its plural ‘intellectuals’ from the first third of the nineteenth century to indicate ‘a category of persons,’ often unfavourably.
In his book, Marxism, Intellectuals and Politics (2006), D. Bates also quotes Raymond Williams:
In Byron’s remark, as Raymond Williams has noted, we see a view of the intellectual which implies ‘coldness, abstraction and, significantly, ineffectiveness’ (Williams 1976:141). That is, this early definition of the intellectual contains within it a normative critique of intellectuals as a social group. Yet the point at which most studies begin is with the Dreyfus affair of 1898. In the Dreyfus affair, figures such as Proust and Zola aimed to speak out against the unjust treatment of Captain Alfred Dreyfus (see Arendt 1951; Feuer 1976; Said 1993; Jennings and Kemp-Welch 1997).
So Wikipedia's article does speak the truth, but probably could have provided more details and background for the evolution of the word.