In response to an increasingly ageing world population, the World Health Organization has recently proposed a new framework – called Healthy Ageing – to better cater to older adults’ life needs and desires. This framework calls for transdisciplinary approaches to answer the challenges and opportunities posed by an ageing society. Following this framework, it is argued that the first step to accomplishing the goals of Healthy Ageing is to address the existing biases and stereotypes in the language used for addressing ageing issues. In this paper, we propose a series of linguistic guidelines that can help improve the lexicon used to talk about ageing in design research and practice, by countering many subconscious ageist biases and stereotypes. Ageism, especially in its implicit form, is a pervasive negative force that can affect not only design practitioners and researchers but also older adults, who often use ageist language to describe themselves. The proposed guidelines would also help the “false friends” of ageing people, who may be using apparently innocuous words, terminology, and remarks to refer to ageing, without perhaps realising the underlying ageist attitudes and stereotypes hidden in their used language. Overall, we aim to foster a change in design researchers’ and practitioners’ perspective on ageing, by paving the way for a transdisciplinary discourse on designing for ageing, which could then be further expanded and explored to eliminate ageism in design.