Why is "messenger" the term instead of "messager"? [duplicate]

Just wondering how we got from message to messenger instead of message to *messager?

When and why did this happen with this word? I'm not really interested in the rule so this isn't a duplicate, more interested in this word specifically.

Solution 1:

Both messenger and passenger derive from Anglo-Norman French messager and passager. Those latter are also the standard modern French.

According to the OED etymology the 'intrusive n'before g is a late Middle English development in words such as messenger, passenger, harbinger, nightingale etc. See below:

The β forms show the common late Middle English development of an intrusive n before g (representing both /dʒ/ and /ɡ/ : see E. J. Dobson Eng. Pronunc. 1500–1700 (ed. 2, 1968) II. §438, and compare forms s.vv. passenger n., harbinger n., nightingale n.1), probably strongly reinforced by similar Anglo-Norman and Picard forms with -n- . Forms with ma- probably reflect Anglo-Norman massager (compare forms s.v. message n.); such forms continue to be found (chiefly in East Anglian texts) into the 16th cent.