Evidence-based answer · Last updated · How it’s made
Yes — looking up words is compatible with (and often helps) a comprehensible input approach. Research on glossing and dictionary lookups consistently shows that giving learners quick access to word meanings while they read or listen boosts vocabulary retention and comprehension compared to unglossed input, as long as the looking-up doesn't take over from engaging with the actual meaning of the text. The key is to use lookups lightly, as a support to understanding, not as the main study activity in place of exposure.
Answered for language learning in general. No specific language was set for this question, so the findings are drawn from general second-language research rather than one language’s literature.
Multiple studies and meta-analyses of "glossing" (providing quick definitions in the margin, a pop-up, or a dictionary) found that learners who could look up unfamiliar words while reading remembered more of them than learners reading the same text with no lookup help.3,4,6,7
In plain terms
A large meta-analysis of incidental vocabulary learning (learning words as a byproduct of reading, listening, or watching for meaning rather than deliberately studying them) found real, if modest, gains from comprehension-focused input alone — typically 9-18% of unknown words learned per single exposure session. This shows meaning-focused input works on its own, but it doesn't show that adding lookups makes it worse.2
In plain terms
One study comparing lookups in the learner's native language versus lookups in the target language itself found that less advanced (intermediate) learners understood and remembered more when they looked words up in their own native language, while more advanced learners did better looking things up in the target language.7
Example
In a study comparing Hebrew-speaking and Chinese-speaking learners of English, looking up words only in the native language was tied to lower retention than looking them up in the second language or in both languages together, but this pattern held only for the Chinese-speaking group, not the Hebrew-speaking group — so the best lookup strategy isn't universal across all learners.1
In one classroom study, students who deliberately memorized dictionary definitions of words scored reasonably well on a test of recalling meanings, but did much worse than students who met the same words naturally through a comprehensible reading passage when it came to actually using those words correctly in sentences.5
A meta-analysis of gloss studies found that certain features of how a lookup is presented — such as being clickable/interactive, appearing right in the text rather than as a separate list, or combining a picture with the definition — were associated with stronger vocabulary learning than a bare translation alone.3
Example
In a think-aloud study, learners who had access to word-definition glosses tended to use them just to get a bare minimum understanding of the text (translating word by word) rather than to build a richer mental picture of what they were reading, even when richer glosses (explanatory notes, questions) were available.4
Now pick something to do it with
Each of these opens an overview of the apps, courses and immersion material worth a look for that — filtered to exactly what the advice above points you at:
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