Strictly, the term includes the English Roman Catholics, whom the original draft of the Relief Act of 1779 styled “Protesting Catholic Dissenters”. In practice, however, it designates the “ Protestant Dissenters” referred to in sec. ii. of the Toleration Act of 1688.
The term does not apply to those bodies who dissent from the Established Church of Scotland; and in speaking of members of religious bodies which have seceded from established churches outside Britain one usually employs the term “dissidents“ (from the Latin dissidere, "to dissent"). In this connotation the terms “dissenter” and “dissenting,” which had acquired a somewhat contemptuous flavour, have tended since the middle of the 18th century to be replaced by “nonconformist”, a term which did not originally imply secession, but only refusal to conform in certain particulars (for example the wearing of the surplice) with the authorized usages of the Established Church.
Still more recently the term “nonconformist“ has in its turn, as the political attack on the principle of a state establishment of religion developed, tended to give place to the style of “Free Churches” and "Free Churchman”. All three terms continue in use, “nonconformist” being the most usual, as it is the most colourless.
Original text adapted from the 1911 Encyclopedia Britannica.