Sub Decode()
Dim W1 As Worksheet, W2 As Worksheet, dico, i As Long, Plage As Range, Cel As Range, T1, T2
Set W1 = Worksheets("Feuil1")
Set W2 = Worksheets("Feuil2")
Set dico = CreateObject("Scripting.Dictionary")
'*** définition du dictionnaire de correspondance
T1 = W2.Range("A2:B" & W2.Range("A" & Rows.Count).End(xlUp).Row)
For i = LBound(T1) To UBound(T1)
dico(T1(i, 1)) = T1(i, 2)
Next
'** recherche et écriture
Set Plage = W1.Range("A2:A" & W1.Range("A" & Rows.Count).End(xlUp).Row)
For Each Cel In Plage
T2 = Split(Cel.Value, " ")
For j = LBound(T2) To UBound(T2)
Cel.Offset(, 1) = Cel.Offset(, 1) & " " & dico(T2(j))
Next
Next
End Sub