The improved understanding of the whole healthcare and wellbeing pathway for individuals depends on the power of healthcare information, being made readily available and easily interpretable by both humans and machines. In the centre of this challenge lies the concept of interoperability, as a way to provide fundamental linkage, integration and meaningful use of healthcare data between systems, organisations and users. In particular, semantic interoperability can offer a way of enriching healthcare data with context and meaning, in order to achieve enhanced understanding and better evidence-based interpretation of disease and wellbeing for an individual, within the context of healthcare provision and clinical research. In this keynote paper, the concept of semantic interoperability, for healthcare data linkage and exchange, is critically discussed. An emphasis is given on the importance of clinical terminologies and associated services, as means for adding meaning to routinely collected clinical data.