1 a of weak health; apt to be ill. b (of a person's complexion, look, etc.) languid, faint, or pale, suggesting sickness (a sickly smile). c (of light or colour) faint, pale, feeble.
2 causing ill health (a sickly climate).
3 (of a book etc.) sentimental or mawkish.
4 inducing or connected with nausea (a sickly taste).
5 (of a colour etc.) of an unpleasant shade inducing nausea (a sickly green).
Derivatives:
sickliness n.
Etymology: ME, prob. after ON sjukligr (as SICK(1))
Useful english dictionary. 2012.