XIIIs

XIIIs is the plural form of XIII, the Roman numeral for 13. In writing, it occurs when the numeral thirteen is used as a label or identifier for multiple items. Outside contexts that treat roman numerals as proper names, XIIIs is rare in ordinary prose.

Common contexts include catalogs, editions, or lists that retain roman-numeral numbering; when several items share the XIII designation, editors may render the collection as XIIIs to convey multiplicity. In fiction, branding, or fan-created works, XIIIs may appear as a stylized group name or faction, but this usage is not standardized and depends on the creator's conventions.

Style guides vary on pluralizing numerals used as identifiers. Some recommend avoiding XIIIs and instead recasting the phrase to spell out the count (for example, "the thirteen volumes") or to reframe the heading (for example, "Volume XIII, Part 1"). When writing XIIIs, it is important to avoid ambiguity with XIII's possessive form ("XIII's"), which requires an apostrophe and is a different construction.

In data management and bibliographic records, XIIIs may appear as a header token or code in contexts where roman-numeral labels must be machine-parseable. The meaning of XIIIs is therefore highly contextual and defined by surrounding text.