Dictionary

It's IPA — the International Phonetic Alphabet — where each symbol maps to exactly one sound: /ˈ/ marks the stressed syllable (the most useful single symbol: /ˈrɛkərd/ the noun vs /rɪˈkɔːrd/ the verb), /ə/ is the neutral 'uh' (the most common sound in English), /iː/ the long ee, /ʃ/ the sh. You don't need to learn it all — the audio button says the word for you — but stress marks alone fix most mispronunciations, since English speakers forgive wrong vowels far more readily than wrong stress.

Three usual causes, in order: inflected forms — dictionaries list base forms, so try 'run' not 'running,' 'goose' not 'geese'; spelling — English is hostile, and if you're close but wrong, working from the pronunciation often helps; and genuine gaps — the underlying Wiktionary data is vast but not infinite, thinnest on highly technical jargon and very recent slang (though it beats print dictionaries on the latter). Compound phrases ('once in a blue moon') are hit-or-miss; try the head word.

Honest tiering: for 'what does this word mean and how is it said' — the question behind nearly every dictionary lookup — this is fully sufficient and faster. The heavyweight dictionaries win on etymology depth, dated usage citations, regional labels, and lexicographic authority — the stuff that settles Scrabble-adjacent arguments and scholarly disputes. Wiktionary-based data is community-maintained, which cuts both ways: quicker on new words, occasionally uneven on rare ones. Use this for reading and writing; cite Merriam-Webster in your dissertation.

The evidence-backed boring answer: encounter words in context and look them up at the moment of curiosity — which is exactly a dictionary-during-reading habit — beats memorizing word lists, because meaning anchors to usage. The chain-lookup design here helps: clicking through synonyms builds the network of related words, and it's the network, not isolated definitions, that makes vocabulary usable. One honest caveat from the thesaurus warning file: understanding a word from one lookup and wielding it correctly are different skills — collect words from reading, deploy them only once you've met them a few times.