Suffix is a morphem added at the end of a root word to form a new word with a new meaning. Suffix -er has a lot of meanings. Take a look at this:
1. as a performer; a person or a thing who/which does something
Suffix -er (also -or) is added to some verbs to form nouns that refer to people or things that do that particular activity.
• a singer = a person who sings
• a swimmer = a person who swims
• a farmer = a person who farms
• a dishwasher = a machine or person that washes dishes
• an actor = a person who acts
2. as a specialist
Suffix -er is added to the names of particular subjects to form nouns that refer to people who have knowledge about or are studying that subject.
• a philosopher = a person who knows about/studies philosophy
• an astronomer = a person who knows about/studies astronomy
3. to mean “from a certain place”
Suffix -er is added to the names of particular places to form nouns referring to people who come from those places.
• a Londoner = a person who comes from London
• a southerner = a person who comes from the south
4. to mean “to be involved with”
Suffix -er is added to nouns or adjectives to form nouns referring to people who are connected or involved with that particular thing.
• a pensioner = a person who receives a pension
• fifth graders = children who are in the fifth grade in a school
5. to mean “more”
Suffix -er is added to adjectives to mean something is more than another thing; it is mostly used in comparative degree.
Now try this exercise: