"sea swallow" means a mollusc of genus glaucus. It is one of many casual words teens pick up from friends, social media, music or sport, and on its own it carries no particular warning. If you hear your teen use it, it is fair to ask what they mean by it in their friend group, since meanings drift quickly. Asking out of curiosity rather than alarm tends to keep the conversation open and useful.
sea swallow
A mollusc of genus Glaucus.
Definitions
UK
#2·Apr 27, 2026UK
The storm petrel.
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UK
#3·Apr 27, 2026UK
(UK) The common tern ().
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Show 1 more dictionary-style sense (imported)
UK
#1·Apr 27, 2026UK
A mollusc of genus Glaucus.
For parents
"sea swallow" means a mollusc of genus glaucus. It is one of many casual words teens pick up from friends, social media, music or sport, and on its own it carries no particular warning. If you hear your teen use it, it is fair to ask what they mean by it in their friend group, since meanings drift quickly. Asking out of curiosity rather than alarm tends to keep the conversation open and useful.
For ESL learners
"sea swallow" is informal English meaning a mollusc of genus glaucus. It is used widely across English varieties. A more formal or neutral equivalent would be something like "a mollusc of genus glaucus" expressed in standard vocabulary. A common mistake is to assume "sea swallow" can replace its standard equivalent in every register; keep it for spoken or casual situations and use the formal form in writing. If you are a B2 or C1 learner, it is useful to recognise this word when you hear or read it, but think carefully about whether the situation really calls for it before using it yourself.
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For specific readers
Why is this section here?
Slang is read by different audiences for very different reasons. The For parents view re-explains the term in plain, non-judgemental language so a caregiver can understand what their child means without needing the surrounding subculture. The For English learners view focuses on register (when it's safe to use), formal alternatives, and common mistakes — what a textbook won't teach you.
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UK
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🇬🇧About British & Irish slang slang
UK and Irish slang — Cockney, Scouse, Geordie, Yorkshire, Glaswegian, Brummie, Welsh, West Country, plus Irish English. Centuries of regional dialects feeding into modern British and Irish street talk.
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Other words near "sea swallow" (S)
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