A mass of closely packed fat cells (adipose tissue) surrounded by fibrous tissue septa[TMD]. [ http://medical-dictionary.thefreedictionary.com/fat+pad http://purl.obolibrary.org/obo/BTO_0000444 http://amigo.geneontology.org/amigo/term/GO:0060613 ]
An accumulation of adipose tissue (fat cells) enclosed in fibrous tissue[BTO].
FMA says isa fascia organ. Note that XAO and AAO have structures called fat pad/body, but these are gonad-associated, so we place them with the gonad-specific subclass