Peak

Peak can be a verb or a noun. The verb refers to reaching a maximum, or coming to a highest point, literally or figuratively:

• The thunderstorms will last for several days but will peak on Sunday.

The noun refers to the highest point of something, like the peak of a mountain:

• Becoming prime minister was the peak of her career.

Peek

Peek can also be a verb or a noun and is related to sight; it often refers to looking, especially furtively or quickly or through a small space:

• She couldn’t resist opening the box and peeking inside.
• She couldn’t resist opening the box and taking a peek inside.

It’s the word in peekaboo, a traditional game for amusing babies. Peek is also the word in the phrase sneak peek. It might be tempting to think this is sneak peak, but bear in mind that you peek in order to see.

Pique

Pique is the most exotic word of this trio. It comes from a French word meaning ‘to prick’. When people were first piqued in English they were irritated and angry. Pique can still be used  to mean ‘to arouse anger or resentment in’ as in ‘Their rudeness piqued me.’ Now, however, it’s most often our interest or curiosity that gets piqued, meaning that our interest or curiosity is aroused:

• The small door disguised with books piqued her curiosity.

Pique has another meaning too, it is sometimes used to mean ‘to take pride in (oneself),’ as in:

• She piques herself on her dress sense and stylish appearance.

It can also be used as a noun as in:

• She flounced off in a fit of pique.

You might sometimes see the phrase ‘peaked my interest’ but this is a mistake. As we’ve seen, to pique means to arouse, so the correct phrase is ‘piqued my interest’ meaning that my interest was stimulated. Perhaps the confusion arises because of the idea that someone’s interest was taken to a high level, but this is still wrong.