Impossible to understand. It is used in two rather different situations, and it helps to see both.

Impossible to understand無法理解的。It is used in two rather different situations這個字用在兩種相當不同的情況，and it helps to see both了解這兩種情況會有幫助。

First, and most often, about sound: speech you cannot make out. A voice on a bad phone line, someone mumbling, a station announcement swallowed by echo, a drunk person, a singer whose words disappear into the music. Here the problem is not the ideas — it is that you cannot even catch the words. Court and meeting transcripts write "[unintelligible]" where the recording defeats the typist, which tells you the flavour exactly.

First, and most often首先，也是最常見的情況，about sound是關於聲音：speech you cannot make out你聽不出來的說話內容。A voice on a bad phone line電話訊號不好時的聲音、someone mumbling有人講話含糊不清、a station announcement swallowed by echo被回音吃掉的車站廣播、a drunk person喝醉的人、a singer whose words disappear into the music歌詞被音樂蓋過去的歌手。Here the problem is not the ideas這裡的問題不是意思聽不懂——it is that you cannot even catch the words而是你根本聽不出那些字。Court and meeting transcripts write "[unintelligible]"法庭和會議紀錄會寫「[unintelligible]」 where the recording defeats the typist在錄音打敗打字員的地方，which tells you the flavour exactly這正好告訴你這個字的味道。

Second, about writing or explanation: a text so tangled, technical, or badly organised that a reader gets nothing from it. "The instructions were unintelligible." That use carries a hint of blame — you are saying the writer failed, not that you are slow.

Second, about writing or explanation第二種，是關於寫作或說明：a text so tangled, technical, or badly organised一段糾結、太專業，或組織很差的文字，that a reader gets nothing from it讓讀者完全看不懂。"The instructions were unintelligible.""The instructions were unintelligible."（這說明書根本看不懂）That use carries a hint of blame這種用法帶著一點責怪的意味——you are saying the writer failed你是在說寫的人沒寫好，not that you are slow而不是說你自己反應慢。

It is a formal word; in conversation people usually say "I couldn't understand a word" or "it made no sense". Worth knowing that it is absolute in tone: it means *nothing* got through, not that it was difficult.

It is a formal word這是個正式的字；in conversation people usually say口語裡人們通常會說 "I couldn't understand a word" or "it made no sense""I couldn't understand a word"（我一個字都聽不懂）或 "it made no sense"（完全沒道理）。Worth knowing值得知道的是，that it is absolute in tone這個字的語氣是絕對的：it means *nothing* got through意思是完全沒有東西傳達到，not that it was difficult而不是說「有點難懂」。