Lebbaios (Λεββαῖος) is a surname or alternate name for the apostle Thaddaeus, appearing in Matthew 10:3 in some manuscripts as "Thaddaeus who is called Lebbaeus" or simply "Lebbaeus." The name may derive from the Aramaic leb (heart) or libbi (my heart), possibly meaning "courageous" or "beloved" or "man of heart.\”
Lebbaeus/Thaddaeus is one of the most obscure of the Twelve — he is named in the apostle lists (Matthew 10:3; Mark 3:18) but speaks only once in the Gospel accounts (John 14:22), asking Jesus why He will reveal Himself to the disciples but not to the world. Jesus' answer — "Anyone who loves me will obey my teaching... and we will come to them and make our home with them\” — is one of the richest promises of the Spirit in all Scripture.
Lebbaeus' single recorded question yields one of John 14's greatest revelations. The "least" apostle by name recognition becomes the occasion for the deepest Trinitarian promise: Father, Son, and Spirit making their home in the believer who loves and obeys. This is the theology of indwelling — the very heart (leb) of what Lebbaeus' name may point toward.