Thesaurus linguae Latinae (TLL)

A massive dictionary of Latin.  As of December 2019, the project includes A-M, O-P. It is expected to be completed by 2050.

This is not a Latin-English translation dictionary, but more akin to what the Oxford English Dictionary is for English.

It is being provided open access (free) in large PDF chunks on this website.

A New York Times article describes it thus:

Delphi : a history of the center of the ancient world
The last Trojan hero : a cultural history of Virgil's 'Aeneid'
The wisdom of the myths : how Greek mythology can change your life
Greek tragic style : form, language, and interpretation
Space, place, and landscape in ancient Greek literature and culture
Sappho : a new translation of the complete works
Death to tyrants! : ancient Greek democracy and the struggle against tyranny
Demosthenes of Athens and the fall of classical Greece
Libanius the sophist : rhetoric, reality, and religion in the fourth century
Aeschylus's Suppliant women : the tragedy of immigration
Aristophanes' Frogs
Project MUSE
Includes the full text of over 320 scholarly journals in the Arts & Humanities and Social Sciences fields.
Oxford Academic - Oxford University Press Journals and Ebooks

Oxford journals (about 240) and ebooks purchased from Oxford. This does NOT include the Oxford English Dictionary which is on its own platform.

Medieval and Classical Literature Library
Collection of the most important literary works of Classical & Medieval civilization. Search or browse by title, author, genre & language.
JSTOR Comprehensive Collection

Provides access to archival issues of over 4,500 scholarly journals across most academic disciplines. Includes primary source materials.

The collections are the following: Arts & Sciences I to XV, Business IV, Hebrew Journals, Ireland, Life Sciences, Lives of Literature, Public Health, Security Studies, Sustainability, Global Plants, Struggles for Freedom in Southern Africa, World Heritage Sites: Africa, and 19th Century British Pamphlets.

Academic Search Complete
A multi-disciplinary database which provides full text for more than 8,500 periodicals, including full text for over 7,300 peer-reviewed journals.