I'm submitting artwork that uses prints from an office printer, and I want to describe that in the list of mediums used
Pencil is referred to as "graphite" so, is there a term for using an office printer for fine art?
Chris H's comment is the answer in a nutshell: the description should include the medium, and depends on the type of printing. If it's an inkjet print, you can state that; if it's a laser print, the artwork's description could say so. You can also just say 'digital print', combining all digital printing possibilities.
Often the type of paper - if exceptional or otherwise deemed important for the artwork - is also included in the description (e.g. 'giclée print on 210 gr Hahnemuhle Albrecht Durer paper').
Ultimately, though, you describe the print in as much detail as you think is right towards your audience or clients. In some instances you could even be emphatically vague about it if you think it accentuates (the concept of) a particular artwork.
The 'office' in 'office printer' doesn't matter for the technology used, as far as it concerns the quality of the prints, but if you think that fact is important for understanding your piece, it's completely fine to include that.
The art form is called photocopy art, copier art, xerox art or sometimes just xerography with copier art being the most common. It was an experimental art form that originated with artists putting objects on the copy bed and using the copy process to generate the work of art, often manipulating and then recopying multiple times to get the final piece.
That would be different from just using a printer to reproduce an existing work of art. This is specifically art works that use the copier/printer as a tool to give the work its unique qualities.