What is Mutual intelligibility?
Mutual intelligibility is when speakers of two different languages can largely understand each other without study — Swedish, Norwegian and Danish are the textbook trio, and Spanish–Portuguese, Czech–Slovak and Hindi–Urdu are other famous pairs. It's the closest thing to a language-learning discount.
The discounts are asymmetric: Portuguese speakers follow Spanish better than the reverse; Danes read Swedish easily but their swallowed pronunciation baffles Swedes. Writing is usually more intelligible than speech.
For learners, this is strategy: one Scandinavian language effectively unlocks three; Spanish gives you reading access to Portuguese and Italian; Hindi conversation carries into Urdu completely. Choosing a 'hub' language multiplies your investment.
What it means for your speaking
Intelligibility discounts apply mostly to LISTENING and reading — speaking the sibling language still needs its own mouth-training. A Swede understands Danish; speaking Danish is another matter entirely.
Practise out loud — 30 seconds a day →