Famous and infamous

These words are not interchangeable. They are both used to refer to well-known people. If a person is famous, they are well-known for doing admirable things. If a person is infamous, they are well-known for doing despicable things.

• Mother Teresa is famous helping the poor and the needy.
• He is an infamous criminal.

Economic and economical

The words economic and economical are often confused. They are both adjectives with related meanings.

Economic refers to the economy.

• The opposition leader said that the government’s economic policies are in the ruins.

Economical means ‘not wasting money’.

• I am looking for an economical car.

Insure and ensure

To ensure is to guarantee.

• Before going out you have to ensure that the doors are locked.
• We have insured our house against natural calamities like floods and earthquakes.

Flaunt and flout

To flaunt is to show something off.

• If you have it, flaunt it.
• He has just bought a new smartphone, and he likes to flaunt it.

To flout law is to express contempt for it.

Further / farther

There is a common belief that further cannot be used to refer to physical distance. However, this is not exactly true and both further and farther are acceptable in this context.

Envelope and envelop

To envelop is to surround.

• He enveloped her in his arms.

An envelope is a cover for a letter.

• He folded the letter and put it in the envelope.