Middle names are a weird custom.
It's like a semi-secret part of your name that you only randomly use sometimes, and usually only in initials, and which no one else knows except your family.
It is as if the Anglo-Saxons were preparing for a real world Death Note attack I know your true name-style.
Many East Asians, notably Chinese immigrants, choose to adopt a Western name pseudonym to make it easier for Western people who don't speak the language to call them and remember their name.
Cowards! Ciro Santilli would much rather just torture foreigners into learning his language. But fair play.
More interestingly however, some of the names chosen are not typical names, and some end up being very cute or mildly funny. Perhaps it is partly linked to given names are getting weirder.
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A part of speech is a grammatical word category identified by patterns of distribution, combination and, where relevant, inflection. Categories such as noun, verb and adjective help describe what an expression can do in a construction. Meaning is evidence, but a rule equating a category with one broad kind of meaning is insufficient.
For example,
record is a noun in the record and a verb in record the result. The same spelling can therefore require different labels when its context changes. A computational annotation scheme must state whether it assigns categories to lexical entries, individual occurrences or both.[ref]Morphology: General Principles in Universal Dependencies. Part-of-Speech Tags, context, prototypical usage and category distinctions
Universal Dependencies separates a broad part of speech label from additional grammatical features. Two forms can share the label
NOUN while differing in grammatical number. Keeping category and features distinct makes an analysis of a text corpus reproducible without multiplying category labels for every possible form.