Of, pertaining to, or causing death; deadly; mortal; fatal.

Any weapon that causes death. / (genetics) An allele that causes the death of the organism that carries it.

(chemistry) One of the higher alcohols of the paraffine series obtained from spermaceti as a white crystalline solid.

A state of extreme torpor or apathy, especially with lack of emotion, energy or enthusiasm; (loosely) sluggishness, laziness.

sluggish, slow / indifferent, apathetic

The dose of a substance or of radiation likely to cause death (sometimes suffixed with a number).

Any gene that brings about the death of an organism carrying it; usually the result of a mutation.

In a lethargic manner, without energy, tiredly.

In a lethal manner, in manner which is or will be fatal.

The fact of something being lethal; the ability of something to kill. / The rate of death of organisms exposed to something.