Tullio De Mauro's dictionary, free on Internazionale — with frequency labels.
Dictionaries Free IntermediateAdvanced B1–C2
vocabularyreading
Details
About 160,000 entries, and uniquely useful for learners because De Mauro tags words by frequency band (fondamentale, di alto uso, comune…), so you can see at a glance whether a word is worth learning. Definitions are plainer than Treccani's, which makes it the friendlier first monolingual dictionary. Completely free and ad-supported; the interface is dated and there is no app.
Italy's most authoritative monolingual dictionary, free online with etymologies.
Dictionaries Free IntermediateAdvanced B1–C2
vocabularyreading
Details
The reference Italians themselves reach for: full definitions, etymology, usage labels and a synonyms section, alongside Treccani's encyclopedia. Switching to a monolingual dictionary is one of the biggest jumps you can make at B1+, and this is the one to switch to. Entries are dense and written in fairly formal Italian, so keep a bilingual dictionary around for a while; some extras and the ad-free app are paid.
Free multilingual dictionary with etymologies, IPA and full conjugation tables.
DictionariesWebsites Free BeginnerIntermediateAdvanced
vocabularygrammarpronunciation
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Over 100 language editions; the English edition alone has millions of entries covering hundreds of languages, with IPA, declension and conjugation tables, etymologies and usage notes that commercial apps usually paywall. The etymology sections are quietly one of the best vocabulary-retention tools available. Being crowd-sourced, coverage is uneven and rare entries can be wrong — cross-check anything unusual against a native-language dictionary.
Crowd-sourced pronunciations of nearly any word by native speakers.
DictionariesTools Freemium BeginnerIntermediateAdvanced
pronunciationlistening
Details
Around 6 million words recorded by native speakers across 400+ languages, usually with several accents per word so you can hear regional variation. Free to search on the site; the paid tiers are aimed at API users and bulk audio downloads. Indispensable for names, place names and anything a TTS voice would mangle — many learners wire it directly into Anki for card audio.