Wiktionary
n. (context photography English) A print made by exposing the printing paper to light through a negative that is placed directly onto it
WordNet
n. a print made by exposing a photosensitive surface to direct contact with a photographic negative
Wikipedia
A contact print is a photographic image produced from film; sometimes from a film negative, and sometimes from a film positive. In a darkroom an exposed and developed piece of photographic film is placed emulsion side down, in contact with a piece of photographic paper, light is briefly shone through the negative and then the paper is developed to reveal the final print.
The defining characteristic of a contact print is that the resulting print is the same size as the original, rather than having been projected through an enlarger.