mkdict: 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 CentOS possible default full paths are:

/usr/sbin/mkdict - from package: cracklib-dicts

You may install the required package with command yum install {package}

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