Good guess, but no cigar. Luckily, I have access to the OED online, and it is (as I had guessed) cognate with French "Dom" (with today's "Dom" too): Sir or Master. Notice that the OED cites the very edition of the Four Sons that you are reading. How's that for recursive?
dam | damp, n.4
Quotations:
Etymology: < Old French dam (also dan, domp, dant, in nominative dans, danz) < Latin ... (Show More) Obs. Thesaurus »
Lord; as a prefix = Sir, Master. Cf. dan n.2 ▸c1300 Havelok (Laud) (1868) 2468 He knew, þe swike dam, Euerildel god was him gram. c1375 Lay Folks Mass Bk. (MS. B.) 18 Dam Ieremy [v.rr. Dane Ieremi, Saynte Ierome] was his name. 1506 in S. Tymms Wills & Inventories Bury St. Edmunds (1850) 108 Dame John Barkyng, pytauncer of the monasterij in Bury. c1386 Chaucer Nun's Priest's Prol. (Harl.) 26 Wherfor sir monk, damp Pieres by ȝour name. 1490 Caxton tr. Foure Sonnes of Aymon (1885) xvi. 382 ‘Damp emperour,’ sayd thenne the duke naymes.
no subject
dam | damp, n.4
Quotations:
Etymology: < Old French dam (also dan, domp, dant, in nominative dans, danz) < Latin ... (Show More)
Obs.
Thesaurus »
Lord; as a prefix = Sir, Master. Cf. dan n.2
▸c1300 Havelok (Laud) (1868) 2468 He knew, þe swike dam, Euerildel god was him gram.
c1375 Lay Folks Mass Bk. (MS. B.) 18 Dam Ieremy [v.rr. Dane Ieremi, Saynte Ierome] was his name.
1506 in S. Tymms Wills & Inventories Bury St. Edmunds (1850) 108 Dame John Barkyng, pytauncer of the monasterij in Bury.
c1386 Chaucer Nun's Priest's Prol. (Harl.) 26 Wherfor sir monk, damp Pieres by ȝour name.
1490 Caxton tr. Foure Sonnes of Aymon (1885) xvi. 382 ‘Damp emperour,’ sayd thenne the duke naymes.