The famous “Lexicon totius Latinitatis” by Egidio Forcellini (very easy to search).
The same, in pdf form.
A Latin-English dictionary (Lewis-Short).
A Latin-French dictionary.
A Latin-French dictionary (the new Gaffiot).
A Latin-German dictionary (Georges).
A Latin-Italian dictionary (Georges-Calonghi).
An online Latin dictionary (in French).
IA Latin dictionary, with synonyms, antonyms and a phraseology (Wagner).
“Latin synonyms”, by Schultz (in Italian).
Another treatise on Latin synonyms (in French).
Many links to Latin and Greek dictionaries.
A lot of links to Latin dictionaries and other reference works.
“Latin dictionary and grammar aid.”
A Latin phrasebook.
A dictionary of medieval Latin (Niermeyer, in French and English).
The “Glossarium mediae et infimae Latinitatis”, by Charles du Fresne lord du Cange (in Latin).
A Latin-German dictionary: from Petrarch to the year 1700.
An Italian-Latin dictionary (Calonghi-Rivoire).
An Italian-English dictionary of neologisms.
A Spanish-Latin dictionary of modern words.
An English-Latin dictionary: to translate modern words into Latin.
The best Greek dictionary (Liddel-Scott).