See the etymology of the corresponding lemma form.
Adjective
multum
inflection of multus:
accusative masculine singular
nominative/accusative/vocative neuter singular
References
“multum”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
“multum”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
multum in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
multum in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
Carl Meißner, Henry William Auden (1894) Latin Phrase-Book[1], London: Macmillan and Co.
Morwood, James. A Latin Grammar. Oxford: Oxford University Press, 1999.
Polish
Etymology
Borrowed from Latinmultum.
Pronunciation
IPA(key): /ˈmul.tum/
Rhymes: -ultum
Syllabification: mul‧tum
Pronoun
multum
many, a lot of [+genitive]
Further reading
multum in Wielki słownik języka polskiego, Instytut Języka Polskiego PAN