Definition of "deletorious"

And no maruell. For, the leaues of Boxe be deletorious, poiſonous, deadlie, and to the bodie of man very noiſome, dangerous and peſtilent […]

1587, Leuinus Lemnius, translated by Thomas Newton, An Herball to the Bible […] ‎, London: Edmund Bollifant, page 207

[…] of which there are various kinds, all of them of a deletorious quality, ſome in a greater and others in a leſſer degree […]

1782, William Raley, “Preface”, in A Treatise on the Management of Potatoes‎, York, page iv

Mutations are mostly deletorious and recessive and carried by heterozygous individuals. So most of them are of no practical value since mutants are unable to compete with the wild type.

2006, Dr. Sidharth Arora, “Genes and Chromosomes”, in A Treatise on the Management of Potatoes‎, New Delhi: Laxmi Publications Pvt Limited, page 119