Habitually ailing or indisposed; not sound or strong as regards health or natural vigor; liable to be or become sick: as, a sickly person, animal, or plant; a sickly family.Pertaining to or arising from a state of impaired health; characteristic of an unhealthy condition: as, a sickly complexion; the sickly look of a person, an animal, or a tree.Pertaining to sickness or the sick; suitable for a sick person.Marked by the presence or prevalence of sickness: as, a sickly town; the season is very sickly.Causing sickness, in any sense; producing malady, disease, nausea, or disgust; debilitating; nauseating; mawkish: as, a sickly climate; sickly fogs; sickly fare.Manifesting a disordered or enfeebled condition of mind; mentally unsound or weak: as, sickly sentimentality.Synonyms Unwell, Ill, etc. See sick.In a sick, sickly, or feeble manner; so as to show ill health or debility.To make sickly; give a sickly or unhealthy appearance to.