Cambridge dictionary defines carbon footprint as
Someone's carbon footprint is a measurement of the amount of carbon dioxide that their activities produce. (https://dictionary.cambridge.org/dictionary/english/carbon-footprint)
The terms carbon footprint and environmental footprint often get mixed up but the terms have different definitions. For the definition of environmental footprint, click here.
Environmental scientists Thomas Wiedmann’s and Jan Minx’ elaborate definition of the carbon footprint:
The carbon footprint is a measure of the exclusive total amount of carbon dioxide emissions that is directly and indirectly caused by an activity or is accumulated over the life stages of a product. This includes activities of individuals, populations, governments, companies, organisations, processes, industry sectors etc. Products include goods and services. In any case, all direct (on-site, internal) and indirect emissions (off-site, external, embodied, upstream, downstream) need to be taken into account. (Wiedmann and Minx, Ecological Economics Research Trends, “A definition of ‘Carbon Footprint’,” p. 5)
In the context of the European Union’s statements on the carbon footprint and the causes of climate change:
By releasing more of the gases that trap heat into the atmosphere, we are causing the temperature on Earth to rise at an extraordinary rate. [...] Our carbon footprint measures the impact we have on the planet in terms of the amount of greenhouse gases we produce in our daily lives, for example, how much fuel and power we use or is needed to make the things we use. (https://ec.europa.eu/clima/sites/youth/causes_en)