Words ending
in -ary.

No common root word

A day that marks the date something happened in an earlier year.

“My parents celebrated their wedding anniversary.”

bound → boundary

A line that marks the edge of an area.

“The river forms the boundary between the two farms.”

custom → customary

Usual, because it is a custom.

“It is customary to shake hands after the game.”

No common root word

A book in which you write what happens each day.

“I wrote about the trip in my diary.”

No common root word

A book or website that lists words and their meanings.

“Look up the word in the dictionary.”

diet → dietary

To do with the food you eat.

“He has a dietary need: he can't eat nuts.”

document → documentary

A film or programme about real people and events.

“We watched a documentary about penguins.”

element → elementary

Simple and basic.

“We started with some elementary maths problems.”

imagine → imaginary

Not real; only in the mind.

“My little sister has an imaginary friend.”

legend → legendary

Very famous, or told about in legends.

“The team's goalkeeper is legendary.”

No common root word

A place where books are kept for people to read or borrow.

“I borrowed three books from the library.”

No common root word

To do with soldiers or the armed forces.

“The military band marched past.”

mission → missionary

A person sent to another country to spread their religion.

“The missionary started a school in the village.”

moment → momentary

Lasting only a moment.

“There was a momentary pause before everyone cheered.”

No common root word

Needed; must be done.

“It is necessary to wear a helmet when you ride your bike.”

No common root word

Normal; not special or different.

“It was an ordinary Tuesday until the snow came.”

planet → planetary

To do with planets.

“Our class built a model of the planetary system.”

No common root word

First or most important.

“Our primary aim is to have fun.”

revolution → revolutionary

Bringing a huge change, or to do with a revolution.

“The telephone was a revolutionary invention.”

No common root word

Money a person is paid regularly for their job.

“The new job has a bigger salary.”

second → secondary

Coming second, or less important.

“For our team, winning is secondary to having fun.”

station → stationary

Not moving.

“The bus was stationary at the red light.”

No common root word

A short version of something that gives only the main points.

“Write a summary of the story in three sentences.”

No common root word

Lasting only a short time.

“We are in a temporary classroom while the roof is fixed.”

No common root word

All the words a person knows or uses.

“Reading helps you grow your vocabulary.”