O for Orange

O

/əʊ/ noun: O; plural noun: O's or Os

There are different Usages of the letter O.

1. the fifteenth letter of the English alphabet

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

This letter denotes the next after N in a set of items, categories, sizes, etc. e.g. It also denotes the fifteenth of fifteen or more hypothetical people or things.

2. Abbreviations 

O = zero specially when spoken. O = Oh as exclamation. O' = Of with apostrophe. In some scientific notations especially structural chemistry o = ortho as in o-xylene.

3. Science

In Chemistry O = Oxygen the eighth element of the periodic table.

The most Common Noun which is used to learn this letter at the Nursery level is Orange; O for Orange.