n. A man who seeks sexual or romantic relationships with significantly older women.
Similar to panthers (younger women dating older men) and their counterparts, manthers (older men dating younger women), granthers are younger men dating grandmother-aged women.
A 67 year old cougar signed up for a senior online dating site and was surprised at how many granthers in their 20s, 30s and 40s asked her out.
A man in his late 50s or older that has grandkids and is divorced, widowered, or single. He also frequents local establishments looking for women his kids age, or even younger (his grandkids' age). This man is still on his "game" (due to advances in modern medicine usually perscribed). Recognizable by a scotch in one hand and his black card in the other. His golden chain entwined in his executive silver chest hair protruding from his unbuttoned shirt.
Hugh Hefner has been a granther to many of the women he has had in the past 20 years.