infra red vs. infrared

[Thunu]

English Language Tests, Intermediate level

ESL/EFL Test #161 "Mobile telecommunication expressions", question 4

You can transfer data between two cellular phones by using the ......... connection located on the front of your phone.

(a) hands free
(b) main
(c) infra red
(d) charger

English Language Tests, Intermediate level

ESL/EFL Test #161 "Mobile telecommunication expressions", answer 4

You can transfer data between two cellular phones by using the infra red connection located on the front of your phone.

Correct answer: (c) infra red

Your answer was: incorrect
You can transfer data between two cellular phones by using the main connection located on the front of your phone.
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Dear Teachers

Is it "infra red" or "infrared" and what does it mean in this sentence?

Thank you
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Reach an agreement as ploughing, don't let argument happen at crops.

[Mister Micawber]

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The meanings are the same. The usual spelling is 'infrared'.
.
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Native English teacher at Mister Micawber's