Third-person singular simple present indicative form of knock.(verb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "knocks" in a sentence
"(_Two knocks are heard outside the door down_ L. _After five seconds two further knocks_."
"The Benedictine sisters even assert that they are warned of their approaching dissolution by some nocturnal noise, which they call the knocks of St. Benedict."
"The rain knocks the small blossoms from the trees and the tree will only produce nectar when the sun is shining."