身邊沒有人跟著
最直接的一支：空位上本來該站著的是一個人。
adjective · B2
With no one else there — a person who is travelling, waiting, or going somewhere with no companion or adult beside them, or a bag or package left with nobody looking after it.
沒有人陪同的
核心畫面
One way to hold this word: picture a space beside someone that is meant to be filled, and it is empty. A child walks to the gate and no adult walks with her. A suitcase goes round the belt and its owner is on another flight. A voice rises in a hall and no piano comes in under it. The word does not say the person is lonely or the music is poor. It only reports the empty place at the side.
可以想成「旁邊那個位置空著」。本來該有人走在旁邊、坐在旁邊，或者在音樂裡跟著一起響，結果那裡沒有人。小孩走向登機門，…更多收起
可以想成「旁邊那個位置空著」。本來該有人走在旁邊、坐在旁邊，或者在音樂裡跟著一起響，結果那裡沒有人。小孩走向登機門，旁邊沒有大人。行李在轉盤上轉，主人不在同一班飛機。歌聲在廳裡響起，底下沒有鋼琴接住。unaccompanied 不評價寂寞，也不評價好壞，它只是指出那個空位。看懂這個畫面，人、行李、音樂、甚至抽象的「該跟著來的事」，就都通了。From the word’s history
Wiktionary records the word simply as un- + accompanied. Accompany carries the idea of going along beside someone, so un- takes that companion away and leaves the space open.
維基詞典把這個字記成 un-（沒有）加上 accompanied。accompany 本來是「陪著一起走」，un- 把那個陪的人拿掉，於是旁邊就空了出來。這正好是今天各種用法共通的畫面。
Wiktionary entry for unaccompanied, kaikki:3f6f69a190036ae4:866169946:5846 — "From un- + accompanied."
Three branches
沒有伴奏，只有一個聲音
把「陪在旁邊的人」換成「墊在底下的聲音」，同一個空位就搬進了音樂裡。
adjective · B2
Singing or playing with no other voice or instrument sounding at the same time. It also describes music that is written to be performed by one voice or one instrument on its own.
無伴奏的
少了該跟著來的那件事（固定說法 unaccompanied by）
空位上的不再是人或聲音，而是一件你預期會同時出現的事；這一支只活在 unaccompanied by 這個句型裡。
adjective · C1
Happening or existing without a second thing that you would expect to come with it. This is a formal way of saying 'without', and it is nearly always followed by 'by'.
沒有伴隨著…