Definition of mossbacks:
(n) :
(informal) Synonym of mossyback (“a person with old-fashioned views; hence, one who is very conservative or reactionary”).
(n) :
(fishing) Synonym of mossyback (“a fish that is large and old, especially one that has algae growing on its back”).
(n) :
A turtle that, because of its age, has a growth of algae on its back
(n) :
A common snapping turtle (Chelydra serpentina).
(n) :
A largemouth bass or moss bass (Micropterus salmoides).
(n) :
Senses relating to animals.