naked eye

Idioms  

1. Sight unassisted by an instrument such as a microscope or telescope. For example, These insects are too small to be seen with the naked eye. This expression was first recorded in 1664.

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Example Sentences

"While a laser looks to the naked eye like a steady beam, there's actually a lot of fluctuation, which causes noise when you're using lasers for measurement," says Vamivakas.

From Science Daily

Unlike many previous experiments, this system is visible to the naked eye and operates on a compact device about one foot tall that can be held in your hand.

From Science Daily

Invisible to the naked eye, GPS jamming can cause significant disruption, hampered communications – and potentially deadly accidents.

From BBC

To the naked eye, their house was spotless, apart from a recently-used mop.

From BBC

In other words, their DNA reveals differences that cannot be seen with the naked eye.

From Science Daily