A1 used before a noun to refer to a single thing or person that has not been mentioned before, especially when you are not referring to a particular thing or person:

A1 used to say what type of thing or person something or someone is:

A1 used to mean any or every thing or person of the type you are referring to:

used before some uncountable nouns when you want to limit their meaning in some way, such as when describing them more completely or referring to one example of them:

A2 used before some nouns of action when referring to one example of the action:

A2 used when referring to a unit or container of something, especially something you eat or drink:

A2 used before the first but not the second of two nouns that are referred to as one unit:

A2 used before some words that express a number or amount:

used in front of a person's name when referring to someone who you do not know:

used in front of someone's family name when they are a member of that family:

used before the name of a day or month to refer to one example of it:

A1 one:

A2 used between a fraction and a unit of measurement:

A2 used when saying how often something happens in a certain period:

A2 used when saying how much someone earns or how much something costs in a certain period:

written abbreviation for amp noun