Tuanis
Cool, great, all sorted — the tico stamp of approval, with an etymology nobody has settled.
Related lesson: Costa Rican Spanish: A Survival Guide.
Hear it in context
—¿Nos vemos a las ocho? —Tuanis.
'Shall we meet at eight?' 'Cool.'
Qué tuanis la fiesta del sábado, mae.
Saturday's party was brilliant, mate.
Todo tuanis por acá, no se preocupe.
Everything's fine here, don't worry.
What It Actually Means
Tuanis is the Costa Rican word for good, cool, nice, fine and sorted, applied to plans, parties, objects and — carefully — people. Grammatically it behaves like an indeclinable adjective and doubles as a complete utterance, so tuanis on its own can mean “agreed”, “great” or “no problem”. It is the local occupant of the slot Colombia fills with chévere and Argentina with buena onda.
The Two Stories
Nobody has settled where it came from, and both candidates have believers. The popular one derives it from English “too nice”, arriving through the Caribbean coast and American contact — tidy, memorable and entirely undocumented. The other credits malespín, the nineteenth-century Central American code that swaps letters in pairs (a↔e, i↔o, b↔t, m↔p, f↔g), under which bueno comes out as tueno and thence tuanis. The malespín account is helped by the word turning up in Nicaragua and Honduras too, well away from any English contact — but “helped by” is not “proven”, and this entry endorses neither.
How Natives Use It
Informally and cheerfully, mostly in speech, mostly among people who are already comfortable with each other. It attaches to the standard exclamative (qué tuanis), to totalisers (todo tuanis), and to plain assent. Some younger ticos hear it as faintly of another decade and reach for pura vida instead, but nobody would call it dead.
Common Pitfall
Do not try to conjugate, pluralise or feminise it; the -s is part of the word, not a plural. And watch the register — tuanis is friendly street Spanish, so it belongs in a bar and not in an email to a landlord, where muy bien does the job without the costume.