To interpret an adjectival nickname we must go to its meaning in Chaucer and his contemporaries. Silly, Seeley, Seely
"This sely, innocent Custance" (B, 682)—
still means innocent when we speak of the "silly sheep," and happy in the phrase "silly Suffolk." It is cognate with Ger. selig, blessed, often used in speaking of the dead. We have compounds in Sillilant, simple child (Chapter X), and Selibarn. Seely was also used for Cecil or Cecilia. Sadd was once sedate and steadfast
"But thogh this mayde tendre were of age,
Yet in the brest of hire virginitee
Ther was enclosed rype and sad corage"
(E, 218);
and as late as 1660 we find a book in defence of Charles I. described as—
"A sad and impartial inquiry whether the King or Parliament began the war."
Stout, valiant, now used euphemistically for fat, is cognate with Ger. stolz, proud, and possibly with Lat. stultus, foolish. The three ideas are not incompatible, for fools are notoriously proud of their folly and are said to be less subject to fear than the angels. Sturdy, Sturdee, once meant rebellious, pig-headed—
"Sturdy, unbuxum, rebellis, contumax, inobediens." (Prompt. Parv.)
Cotgrave offers a much wider choice for the French original—