neat

Clean, tidy; free from dirt or impurities.

My room is neat because I tidied it this morning.  She has very neat hair.

Then his sallow face brightened, for the hall had been carefully furnished, and was very clean. ¶ There was a neat hat-and-umbrella stand, and the stranger's weary feet fell soft on a good, serviceable dark-red drugget, which matched in colour the flock-paper on the walls.

Free from contaminants; unadulterated, undiluted. Particularly of liquor and cocktails; see usage below.

I like my whisky neat.

1595, George Peele, The Old Wives’ Tale, The Malone Society Reprints, 1908, lines 464-465, A cup of neate wine of Orleance, That never came neer the brewers of England.

Conditions with a liquid reagent or gas performed with no standard solvent or cosolvent.

The Arbuzov reaction is performed by adding the bromide to the phosphite, neat.  The molecular beam was neat acetylene.

With all deductions or allowances made; net.

Why without telling the least title of Falshood, within the space of the last Week’s Play, the Gains of Count Cog, really amounted to no less than Twenty Thousand Pounds Sterling neat Money.

Dr. Swift […] says, in his short view of the state of Ireland, that the whole cash of that kingdom amounted to 500,000 l. that out of this they remitted every year a neat million to England, and had scarce any other source to compensate themselves from […]

Having a simple elegance or style; clean, trim, tidy, tasteful.

The front room was neat and carefully arranged for the guests.

Used to signify a job well done.

Used to signify approval.

An artificial intelligence researcher who believes that solutions should be elegant, clear and provably correct. Compare scruffy.