The word instrument is defined as an object that is used for producing a musical sound, or one which gives an accompanying noise. There are many instruments in the world and it can sometimes be difficult to spell them. Here are the rules: 1. If a word is followed by an s then the s is dropped. 2. If a word ends in n or nn then the n is dropped. 3. If a preceding letter of a word ends in o or oo then that o becomes silent and you add an e to make it as short as in words such as low, low/yeah, and a no-no. 4. If there is a prefix such as re-, for example, it will usually be pronounced with an initial r sound at the beginning, even though that is not the spelling. 5. If a word ends in ea or ie then you add -e to make it short. 6. If a word ends in ee then you add -ee to make it short (as in words such as date, dew, and toe). 7. There are a few exceptions to the rule. When you are spelling words, be sure to look up the words in a dictionary and find out how they should be correctly spelled.