Millimetrum
Millimetrum is a term encountered primarily in Neo-Latin writings and in speculative fiction to denote a unit of length equal to one thousandth of a metre. It is not part of the official International System of Units (SI), and it has no standardized symbol or spelling in contemporary scientific usage.
Etymology and form: The name combines Latin mille (thousand) and metrum (measure). In actual practice, modern
Relation to the millimetre: The standard SI unit of length is the metre, with the millimetre (symbol
Usage in literature and media: In science-fiction settings or in Neo-Latin glossaries, millimetrum may be invoked