dict_lookup: command not found

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

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

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/dict_lookup - from package: dict

You may install the required package with command apt-get install {package}

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