adj

• (obsolete) Marked by the occurrence of illness or disease (of a period of time).
  "This physic but prolongs thy sickly days."
• (obsolete) Tending to produce disease or poor health.
  "a sickly autumn; a sickly climate"

verb

• (transitive, archaic, literary) To make (something) sickly.
  "Thus conscience does make cowards of us all, And thus the native hue of resolution Is sicklied o’er with the pale cast of thought,"
• (intransitive, rare) To become sickly.
  "1889, Samuel Cox, An Expositor’s Notebook, London: Richard D. Dickinson, 7th edition, Chapter 26, p. 364, But the seven most prominent Apostles […] still hang together, their hearts tormented with eager yet sad questionings, their hopes fast sicklying over with the pale hues of doubt."