How to pronounce Horizon /həˈraɪ.zən/ and horizontal /ˌhɔːr.ɪˈzɑːn.t̬əl/

horizon
noun [ S ]
 US
/həˈraɪ.zən/

UK
/həˈraɪ.zən/

the line at the farthest place that you can see, where the sky seems to touch the land or sea:

The moon rose slowly above the horizon.

https://dictionary.cambridge.org/dictionary/english/horizon?q=HORIZON

https://dictionary.cambridge.org/dictionary/english/horizontal

horizontal
adjective
UK
/ˌhɒr.ɪˈzɒn.təl/ US
/ˌhɔːr.ɪˈzɑːn.t̬əl/

C1
parallel to the ground or to the bottom or top edge of something:

Draw a horizontal line across the bottom of the page.
Keep the patient horizontal with the feet slightly raised.
Compare
vertical adjective

expand your horizons – phr. increase the number of things that you know about, have experienced, or can do

She wrote that ingenuity is what permits us “to accomplish amazing things” and “expand our horizons to the edges of the universe."

helicopter
noun [ C ]
UK
/ˈhel.ɪˌkɒp.tər/ US
/ˈhel.əˌkɑːp.tɚ/
(informal copter)

https://dictionary.cambridge.org/dictionary/english/helicopter

A2
a type of aircraft without wings, that has one or two sets of large blades that go round very fast on top. It can land and take off vertically and can stay in one place in the air:

The injured were ferried to hospital by helicopter.