subdued
adjective: tamed, or gently dominated
mourn
verb: to grieve or experience sorrow
scorn
noun: contempt or deliberate act of snubbing or ignoring
languish
verb: to become weak or feeble, often from an unpleasant or trying experience
winged god
noun: Eros (Greek) or Cupid (Roman), a minor god of love who is said to shoot people with arrows to make them fall in love. Apparently, the speaker has been shot twice.
crossed
verb: stymied, stopped, or betrayed
if it chance
prepositional phrase: archaic way of saying "if it so happens," or "by chance," or "If I am lucky."
'twixt
preposition: contracted form of "betwixt", an archaic word for "between"
fever in (my) blood
adjectival phrase: a lusting for; a feeling of passion
dart
noun: arrow; in this context referring specifically to Cupid's arrows, which inspire those they pierce to fall in love with the first person they see