lessen

Etymology

From Middle English lessenen, lasnen, equivalent to less + -en (verbal suffix).

verb

1. (transitive) To make less; to diminish; to reduce.
   a. 1686, Benjamin Calamy, a sermon Charity […] shall lessen his punishment.
   December 6, 1709, Francis Atterbury, a sermon preach'd before the sons of the clergy at their anniversary-meeting in the Church of St. Paul St. Paul chose to magnify his office when ill men conspired to lessen it.
   The thin glass that makes mirror tiles light in weight also tends to lessen their reflective quality. 1980, Robert M. Jones, editor, Walls and Ceilings, Time-Life Books, page 44
   Many hospitals have not taken simple steps to lessen the distress and confusion which dementia sufferers' often feel on being somewhere so unfamiliar – such as making signs large and easy to read, using colour schemes to help patients find their way around unfamiliar wards and not putting family mementoes such as photographs nearby. December 16, 2011, Denis Campbell, “Hospital staff 'lack skills to cope with dementia patients'”, in Guardian
2. (intransitive) To become less.

conj

1. (nonstandard, dialect) unless.
   Ober closed his encomium with the serious statement that “Lessen he could marry Miss Jennie he would be a bachelor the balance of his life," to which the drayman replied that " If Oi were Miss Janie Oi'd black yer oi the minute ye thought of such a thing. The oidee." 1895, Book-keeper (Detroit, Mich. : 1888). - Volume 8, Issue 6, page 10
   She was fine-looking; he couldn't find a fault with her 'lessen he made it up. 2011, Caroline Miller, Lamb in His Bosom, page 107
   No more work outta them lessen they paid now. 2011, J. California Cooper, Family
   That usually all they need fuh go that straight and narrow path, lessen they got that real badness or foolishness in them. 2013, Lornabelle Gethers, Honey Bea's Everlasting Gift, page 88