A weirdlang is typically just a normal language with weird syntax, but nothing else truly esoteric about it.
In contrast with True Esolangs
A True Esolang (that is, an esolang that is not a weirdlang) has to have something strange about the semantics, structure and/or some other form of esoterism. A language with strange semantics would be Malbolge and one with strange structure would be Befunge. A True Esolang still may have strange syntax, but that cannot be the only thing making it a True Esolang.
- LOLCODE is a weirdlang because, aside from the lulzy keywords, it's just a normal language.
- If brainfuck was a normal language, Ook! would be a weirdlang.
It should be noted that, while many don't usually find them as interesting and entertaining as "True" Esolangs, not all weirdlangs are bad. For example, Vowels, a language with an interesting concept, is really just a low-level assembly language with weird syntax; however, it still forms an interesting idea.
This post about vocabulary- vs logic-based esolangs is a sort-of defense of esolangs that focus on vocabulary (whether or not they are "true esolangs"). It uses the term esolexicons for weirdlangs, emphasizing that the lexicon (set of signifiers) is esoteric, not the rules of the language itself.
On the terms Weird and Esoteric
Confusingly, the term "Weird Language" is sometimes used for esolangs by people who object to the word "esoteric" (usually in academia), most notably Nick Montfort in his essay "Obfuscated Code" and Michael Mateas in his "Weird Languages" (both published in Software Studies, 2005). As Mateas puts it:
- “Esoteric” is a more common term for these languages, but it is a term that could apply to programming languages overall (most people do not know how to program in any language) or to languages such as ML and Prolog, which are common in academia but infrequently used in industry. A better designation might be art languages. However, while such languages are undoubtedly a category of software art, developers of these languages do not use this term themselves, and it seems unfair to apply the term “art,” with all of its connotations, to their work. The term “weird” better captures the intention behind these languages, and is used at times by the language designers themselves.
- "Weird Languages" by Michael Mateas "Software Studies," page 274, note #2, published 2005 http://dm.ncl.ac.uk/courseblog/files/2010/02/softwarestudies.pdf