とんだ

とんだ〈事こと〉になるfor things to take an unexpected (and unwelcome) turn
旅りょ行こうの途と中ちゅうでパスポートを失なくして、とんだことになった。
I lost my passport during the trip, and things took a terrible turn.
とんだ迷めい惑わくa huge/terrible nuisance
近きん所じょの工こう事じはとんだ迷めい惑わくだ。
The construction next door is a real nuisance.
とんだ災さい難なんa terrible misfortune/disaster
彼かれはとんだ災さい難なんに遭あった。
He met with a terrible misfortune.
とんだ人ひと違ちがいan embarrassing case of mistaken identity
とんだ人ひと違ちがいをして、恥はずかしい思おもいをした。
I made an embarrassing mistake by confusing him with someone else.

Kanji

飛fly, skip (pages), scatter

Related words

意い外がいN3sense 1
意外 is a neutral word for 'unexpected', while とんだ adds a strong emotional reaction, usually of surprise or dismay.
大たい変へんN5sense 2
大変 is a versatile word for 'very' or 'terrible' usable in many contexts, while とんだ is limited to pre-noun exclamations of exasperation.
思おもいがけないN2sense 1
思いがけない describes something unforeseen in a fairly neutral way, whereas とんだ usually implies the unexpected event is troublesome or shocking.

Don't confuse with

とんでもないN3sense 2
とんでもない is a predicate i-adjective meaning 'outrageous/absurd' used on its own, while とんだ is a pre-noun adjective that must directly modify a following noun.

Written forms

とんだUsage100%
Standard kana spelling; the kanji form 飛んだ is rarely used.
飛とんだ
rarely-used kanji form
Rarely used kanji form; learners should use the kana spelling.

Etymology

Derived from the verb 飛ぶ (とぶ, 'to fly'), with the past/perfective form 飛んだ (とんだ) taking on a figurative meaning of 'unexpected' or 'outrageous'. The exact semantic shift is uncertain, but it likely developed from the idea of something 'flying' beyond normal bounds.