Etymology 1
From bed + -er (agent noun suffix).
Etymology 2
From bed + -er (measurement suffix).
Noun
bedder (plural bedders)
- (in combination, informal) A property with a specified number of bedrooms.
2006, Liz Hodgkinson, The Complete Guide to Renovating and Improving Your Property:From looking round, I realized that the gap in the market was for smart one-bedders in central locations.
2014 January 10, Hilary Osborne, “For sale: four-bedder complete with previous owners”, in The Guardian:
2017 August 7, “A 3-bedder condo with space for a family of three”, in Lookbox Living:The main gripe with new condominiums these days is the lack of space, and that was apparent in this three-bedder unit with its small bedrooms and communal spaces.
2020 October 3, Ryan Ong, “Why two-bedroom units could be the safest choice for rental income”, in 99.co:Well if it’s a two-bedder, it’s not too big a problem. Such units are still big enough for her and her partner, and maybe their first child too.
References
"Bedders, Bulldogs and Bedells: A Cambridge Glossary" By Frank Stubbings,Cambridge University Press,1995