File. At least in POSIX-compliant systems.
3.164 File
An object that can be written to, or read from, or both. A file has certain attributes, including access permissions and type. File types include regular file, character special file, block special file, FIFO special file, symbolic link, socket, and directory. Other types of files may be supported by the implementation.
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People saying "files" when they mean only "regular files" are not really POSIX-compliant. :)
You can learn what POSIX is from answers to this question. Various operating systems are POSIX-compliant (fully or mostly) or not. Without going into details, this answer applies to Unix and Unix-like systems (including macOS, Linux, BSD), but not to Windows family in general.