Barista is a recently introduced job title that has replaced the more generic ‘the bloke/woman behind the counter’ in establishments such as Starbucks, Café Nero and Costa Lotta.
It is probably intended to convey a veneer of specialist knowledge and expertise to regular customers, who often use words such as ‘latte’, ‘arabica’ and ‘mochiato’, all of which mean ‘sludge’ in their original language.
The collective noun for baristas is a fantoosh or, more rarely, a bombast.
If you have been charged with a serious criminal offence, it is a false economy to engage a barista to defend you against the charges. In such cases, you’re almost certainly better off relying on the services of a bar mitzvah.