I. ˈpləs adjective
Etymology: Latin, adverb, more, from neuter of plur-, plus, adjective; akin to Greek pleion more, Latin plenus full — more at full
Date: 1579
1. : algebraically positive
2. : having, receiving, or being in addition to what is anticipated
3.
a. : falling high in a specified range
a grade of C plus
b. : greater than that specified
c. : possessing a specified quality to a high degree
4. : electrically positive
5. : relating to or being a particular one of the two mating types that are required for successful fertilization in sexual reproduction in some lower plantlike organisms (as a fungus)
II. noun
( plural plus·es ˈplə-səz ; also plus·ses )
Date: 1654
1. : plus sign
2. : an added quantity
3. : a positive factor or quality
4. : surplus
III. preposition
Date: 1668
1. : increased by : with the addition of
four plus five
principal plus interest
2. : besides — used chiefly in speech and casual writing
plus all this, as a sedative it has no equal — Groucho Marx
IV. conjunction
Date: circa 1950
1. : and
the Smyth Report, plus an idea and some knowledge of bureaucracy, were all I needed — Pat Frank
eats alone, a hot beef sandwich plus a BLT plus apple pie — Garrison Keillor
2. : in addition to which
it was an achievement. Plus, I wrote the story and the musical score — Jackie Gleason
it's also pretty on my open shelves, plus it smells good — Nikki Giovanni
Usage:
The preposition plus has long been used with a meaning equivalent to and (as in “two plus two”); it is not, therefore, very surprising that in time people have begun to use it as a conjunction much like and. Sense 2 is considered to be an adverb by some commentators. It is used chiefly in speech and in informal writing.