ninthly

This term is an ordinal adverb used primarily in highly structured, formal lists or legalistic enumerations. It is extremely rare in contemporary spoken English and standard prose, where writers typically prefer "ninth" or "the ninth point" to avoid the archaic feel of the -ly suffix.

Because it belongs to a series of sequential adverbs (firstly, secondly, etc.), it is almost never used in isolation. Its appearance signals a rigorous, exhaustive attempt to categorize a large number of points, often appearing in academic treatises or old-fashioned rhetorical arguments.