plus

from The American Heritage® Dictionary of the English Language, 5th Edition.

• conjunction Mathematics Increased by the addition of.
• conjunction Added to; along with.
• conjunction Usage Problem And.
• adjective Positive or on the positive part of a scale.
• adjective Added or extra.
• adjective Informal Increased to a further degree or number.
• adjective Ranking on the higher end of a designated scale.
• adjective Physics Positive.
• adjective Plus-size.
• noun Mathematics The plus sign (+).
• noun A positive quantity.
• noun A favorable condition or factor.

from The Century Dictionary.

• More (by a certain amount); increased (by a specified addition): followed by a noun as an apparent object (a preposition, by, to be supplied): as, the interest plus the disbursements amounts to so much; 6 plus 9 is 15: in this and the next two uses correlative to minus.
• More than nothing; belonging to the positive side, as of an account; above zero, or above the lowest point of positive reckoning: as, a plus quantity in an equation (that is, one having the plus sign, or when initial having no sign, before it).
• Marking more than zero; positive: as, the plus sign.
• In etymology, in composition with; with the addition of (the word or element following): expressed, as in mathematics, by the sign + (see the etymologies in this work). The same sign is occasionally used to indicate cognate or related forms

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Math.) More, required to be added; positive, as distinguished from negative; -- opposed to minus.
• adjective Hence, in a literary sense, additional; real; actual.
• adjective (Math.) the sign (+) which denotes addition, or a positive quantity.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• conjunction sum of the previous one and the following one.
• conjunction colloquial with; having in addition
• conjunction and also; in addition
• noun A positive quantity.
• noun An asset or useful addition.
• noun arithmetic A plus sign: +.
• adjective Being positive rather than negative or zero.
• adjective Positive, or involving advantage.
• adjective physics Electrically positive.
• verb informal To add; to subject to addition.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the arithmetic operation of summing; calculating the sum of two or more numbers
• noun a useful or valuable quality
• adjective involving advantage or good
• adjective on the positive side or higher end of a scale