In chemistry, we use some ordinary words in a very precise way. This means that chemists have to be particularly careful with words like, for example:
addition -(1) Refers to addition reaction or addition transformation; (2) Loosely, the formation of an adduct. (For an example, see Lewis acid); (3) Loosely, any association or attachment.
base - substance which gives off hydroxide ions (OH-) in solution.
compound - a substance formed by the reaction of two or more chemical elements. The elements in a compound are present in fixed ratios. Compounds can be decomposed chemically into their constituent elements.
radical - an atom or group of atoms that contains one or more unpaired electrons (usually very reactive species)
scuff - in flat panel display substrates, the marring of the glass substrate surface, leaving a milky white, grayish, or matte appearance and having appreciable width. [SEMI D9-94]
strain - strain is present in a molecular entity or transition structure if the energy is enhanced because of unfavourable bond lengths, bond angles, or dihedral angles ("torsional strain") relative to a standard.
These words, and many more, have a very precise meaning and cannot be used in a chemistry essay without a great deal of thought. The best way to avoid using a chemical word wrongly is to look it up in a reputable chemical dictionary. Here is a link:
http://www.chemicool.com/dictionary.html.
Acknowledgement: all definitions taken from http://www.chemicool.com/dictionary.html.