Cfrtjryk

Is there a word or phrase meaning to criticise or mock someone without mentioning their name?

On Twitter, people are able to search the site for references to their own name, so people often 'subtweet' other people - tweeting criticism of them without mentioning their name. Google's definition tells me that this only applies to Twitter.

This phenomenon is certainly older than Twitter. The oldest example that I can think of is the (probable) reference to Shakespeare in Robert Greene's 1592 book A Groat's Worth of Wit:

...for there is an upstart Crow, beautified with our feathers, that with his Tygers hart wrapt in a Players hyde, supposes he is as well able to bombast out a blanke verse as the best of you: and being an absolute Johannes fac totum, is in his owne conceit the onely Shake-scene in a countrey.

There are plenty of words for insulting someone - but I think the type of speech where you are talking about someone (whether an insult, compliment etc.) without mentioning their name could be called allusive

From Oxford Dictionary:

Allusive adjective

Using or containing suggestion rather than explicit mention.

Example:

Toby wrote some allusive trash-talk about his ex-girlfriend on social media.

Another expression could be coded.

Coded adjective

1.1 Expressed in an indirect way.

'Coded' is paired with 'insult' pretty often. An example:

John delivered coded insults about his boss during an internal meeting.

Sneak diss, if you're okay with slang:

A sneak diss is when someone makes a rather vague post describing a certain individual in a derogatory way or a situation that multiple people know about, but while describing the person they refrain from using the person's name as to not directly make a connection between the post and the individual. This is a way to keep from being confronted by the post.

[Urban dictionary]

Even though UD's topmost definition talks about its usage in the context of a social media post, the term can be used in real-life situations, as some other definitions on the site show.

The verb dis or diss, short for disrespect, is mainstream enough to have an entry in Oxford:

Speak disrespectfully to or criticize.

‘I don't like her dissing my friends’