The development of social gerontology has led to the emergence of its own terminology and conceptual armoury. ‘Ageism’ has been a key concept in articulating the mission of gerontology and was deliberately intended to act as an equivalent to the concepts of racism and sexism. As a term, it has established itself as a lodestone for thinking about the de-valued and residualised social status of older people in contemporary society. Given this background, ageism has often been used to describe an overarching ideology that operates in society to the detriment of older people and which in large part explains their economic, social and cultural marginality. This paper critiques this approach and suggests an alternative based upon the idea of the social imaginary of the fourth age. It argues that not only is the idea of ageism too totalising and contradictory but that it fails to address key aspects of the corporeality of old age. Adopting the idea of a social imaginary offers a more nuanced theoretical approach to the tensions that are present in later life without reducing them to a single external cause or explanation. In so doing, this leaves the term free to serve, in a purely descriptive manner, as a marker of prejudice.