All yellow things are related through the colour that they share.
On a different and complementary axis, all things containing the spurt of ye-, the roll of l’s, and the elongated smoothness of -ow are related through the sounds that they share.
The word yellow, therefore, can be seen as the medium in which a banana or a NYC taxi becomes related to words like yes, yell, mellow, bellow, etc.
Thoughts fallen by the wayside 