uim-dict-gtk3: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/uim-dict-gtk3 - from package: uim-dict-gtk3

You may install the required package with command apt-get install {package}
Error in other languages:
uim-dict-gtk3: bevel nie gevind nie
uim-dict-gtk3: comandă negăsită
uim-dict-gtk3: comando não encontrado
uim-dict-gtk3: commande introuvable
uim-dict-gtk3: command not found
uim-dict-gtk3: käsku ei ole
uim-dict-gtk3: không tìm thấy lệnh
uim-dict-gtk3: komanda nerasta
uim-dict-gtk3: Kommando nicht gefunden.
uim-dict-gtk3: kommandot finns inte
uim-dict-gtk3: komut yok
uim-dict-gtk3: nie znaleziono polecenia
uim-dict-gtk3: níor aimsíodh an t-ordú
uim-dict-gtk3: no se encontró la orden
uim-dict-gtk3: no s'ha trobat l'ordre
uim-dict-gtk3: opdracht niet gevonden
uim-dict-gtk3: parancs nem található
uim-dict-gtk3: perintah tidak ditemukan
uim-dict-gtk3: príkaz nenájdený
uim-dict-gtk3: příkaz nenalezen
uim-dict-gtk3: команда не найдена
uim-dict-gtk3: командата не е открита
uim-dict-gtk3: 命令找不到
uim-dict-gtk3: コマンドが見つかりません