LADY:
Forms:
OE: hlæfdie, hlǣfdīge
ME: leafdi, levedi → ladi, laddy, ladysse → lady

Etymological constituents:
- a similar original semantic motivation with lord
- hlāf (meaning "bread", "loaf") + a Germanic base dīge (unattested, the same Germanic base as the Gothic digan, to knead, "hníst" (př. těsto))
- compare to: lord (hláfweard , bread-keeper) and servant (hláfǽta, bread-eater)

Phonological development:
late OE and early ME:
- the vowel ǣ – shortened and developed into ĕ and ă
- the second element of the compound, originally -dige, was reduced to -di
14th century:
- the final f → v by partial regressive assimilation
- later completely assimilated to d
from the early 14th century onwards:
- disyllabic word with stressed open syllable
- vowel lengthening in open syllable = two highest long vowels became diphthongs

Primary meaning:
- literally - "one who kneads the bread"
- primarily - a mistress of a household, a woman who has an authority of the servants, lady of the house – now
obsolete, saved in a term landlady, also a queen

Other meanings:
OE - as a title of the Virgin Mary, usually Our Lady, represents the Latin Domina Nostra
12th century – a woman of superior position in society
early 14th century - woman as an object of chivalrous love
1861 – a woman whose manners and sensibilities befit her for high rank in society
since 1890 – an address to any woman

[1]

  1. Oxford English Dictionary.