What does Lēmnius mean in Latin?

Lēmnius, a adjective, means “of, pertaining to, or from Lemnos: Lemnian”.

How do you pronounce Lēmnius?

In classical Latin, [ˈɫeːm.ni.ʊs]; in ecclesiastical (church) Latin, [ˈlɛm.ni.us].

adjectivefirst/second-declension adjective

Lēmnius (feminine Lēmnia, neuter Lēmnium)

Classical[ˈɫeːm.ni.ʊs]Ecclesiastical[ˈlɛm.ni.us]

adjectiverelationalof, pertaining to, or from Lemnos: Lemnian
Comprimit adulescens Lemnius Sicyoniam,c. 203 BCE, Plautus, Cistellaria argumentum.1.1–2
Veniat Aeschylus, non poeta solum, sed etiam Pythagoreus; sic enim accepimus. Quo modo fert apud eum Prometheus dolorem, quem excipit ob furtum Lemnium!c. 45 BCE, Cicero, Tusculanae disputationes 2.23

singular
form	masculine	feminine	neuter
nominative	Lēmnius	Lēmnia	Lēmnium
genitive	Lēmniī	Lēmniae	Lēmniī
dative	Lēmniō	Lēmniae	Lēmniō
accusative	Lēmnium	Lēmniam	Lēmnium
ablative	Lēmniō	Lēmniā	Lēmniō
vocative	Lēmnie	Lēmnia	Lēmnium

plural
form	masculine	feminine	neuter
nominative	Lēmniī	Lēmniae	Lēmnia
genitive	Lēmniōrum	Lēmniārum	Lēmniōrum
dative	Lēmniīs	Lēmniīs	Lēmniīs
accusative	Lēmniōs	Lēmniās	Lēmnia
ablative	Lēmniīs	Lēmniīs	Lēmniīs
vocative	Lēmniī	Lēmniae	Lēmnia

Charlton Lewis's shorter dictionary for students: the same scholarship in plain, modern definitions.

Lēmnius adj.,

of Lemnos, Lemnian, C., O.: pater, i. e. Vulcan, V.—As subst m., Vulcan, O.

Borrowed from Ancient Greek Λήμνῐος (Lḗmnĭos), from Λῆμνος (Lêmnos) + -ῐος (-ĭos).

proper noun · masculinesecond declension

Lēmnius²

Lēmnius m sg (genitive Lēmniī or Lēmnī)

Classical[ˈɫeːm.ni.ʊs]Ecclesiastical[ˈlɛm.ni.us]

poeticVulcan
Lemnius extemplo valvas patefecit eburnas8 CE, Ovidius, Metamorphoses 4.185–186

Borrowed from Ancient Greek Λήμνῐος (Lḗmnĭos), from Λῆμνος (Lêmnos) + -ῐος (-ĭos).