Sweat vs. sweated
Both forms are common and accepted.
Voicemail
It is now usually one word, except in the New York Times and a few other places.
Iteration
an act or instance of saying, doing, or performing something again. The first instance of something can’t be an iteration.
Deprecate vs. depreciate
To depreciate is (1) to lessen in value, or (2) to lower the value of something, especially by falsely undervaluing, disparaging, or belittling it. To deprecate something is to express disapproval of it or to disparage or belittle it. So the two words are synonymous in some uses.
Masterful vs. masterly
Historically they have differed, but today they both mean with virtuosic skill.
Homogenous vs. homogeneous
Homogeneous: (1) of the same or similar nature, and (2) uniform in structure or composition. Homogenous: a scientific word now very often used in place of homogeneous in popular usage.
Ilk
It now has negative connotations.
Data Is or Data Are? – The Singular vs. Plural Debate
Data has evolved beyond its Latin roots and is now usually a singular mass noun, thought it tends to remain the plural form in science, finance, computing, and mathematics.
Deconstruction
It was originally a literary-criticism term, but it’s now widely used in a range of other senses.