
There are some nouns that are only used in the plural.
Examples:
Glasses (eyeglasses), condolences, dark circles (under the eyes), nuptials, grays (white hairs), obsequies (funeral ceremony or honors)
The words indicating the suits in a deck of cards are also only used in the plural: hearts, spades, diamonds, clubs.
Example of use:
He did not deserve any official mourning nor a telegram of condolences from the governor. (Jornal da Tarde)
References: Faraco & Moura



