English compounds of the type x-free usually mean 'free of x' or 'without x', as in trouble-free, tax-free, hassle-free, pain-free, trouble-free, smoke-free, and many other combinations.
These days there are many new meat-free food products on the market. How do food sellers describe them? Using the description meat-free is often only partially informative: it tells you a product has no meat in it, but nothing is said about how the product tastes. Consider this recent newspaper announcement:
Among 11 new plant-based foods going on sale at Tesco this week are centrepiece dishes using the wheat protein favourite seitan as a meat substitute, including a beef-free joint and hunter’s chicken-free traybake. Turkey-free crowns and vegan mince pies are launching in time for Christmas. (The Guardian 29/9/20)
The descriptions beef-free, chicken-free and turkey-free have a literal meaning at their core, namely that the food they describe is 'free of beef', 'free of chicken' and 'free of turkey', but they have acquired an additional meaning. The adjective beef-free actually means 'free of beef, but resembling and tasting like beef', chicken-free means 'free of chicken, but resembling and tasting like chicken' and turkey-free means' free of turkey, but resembling and tasting like turkey'. This is also true for some other combinations: arguably, alcohol-free means 'free of alcohol, but resembling and tasting like alcohol', at least I think this is the intention when you see this description on a beer bottle. It doesn't need to mean this, though. In some cases a product label may simply wish to convey that the drink in question does not contain any alcohol.
On further reflection, I think any of the combinations involving a particular type of meat, e.g. chicken-free, mean something a bit more complex, namely 'free of chicken, or any other meat, but resembling and tasting like chicken'.
Interestingly, meat-free itself does not (or does not necessarily) have the additional meaning 'resembling and tasting like meat'.
What's fascinating is that speakers of English know that beef-free means more than just 'without beef'. If they bought a beef-free steak and it tasted like turkey, they would be very annoyed. Strictly speaking, if they went back to the shop and complained, the shop keeper could say "Why are you complaining? This product really does not contain any beef. It doesn't say anywhere that is should taste like beef." All of this has made life a lot harder for lexicographers.
How does the additional meaning 'resembling and tasting like x' for food products come about?
My theory is that we need to invoke the notion of 'relevance' here: beef in beef-free is mentioned to signal that there is a link between the product being sold and (the taste of) beef. This may seem obvious, but it isn't. Linguists have studied the notion of 'relevance' in social interactions extensively, especially in Relevance Theory. Are there any Relevance Theorists out there who agree with me?