The term wanker is derived from the verb wank in the sense of to masturbate. However, neither the OED nor Etymonline can trace it further back than that: both claim it is of “obscure origin”, which just means they don’t know.
As with my question on snogging, this term seems to have come into vogue around the mid-20th century, but nobody knows where or how it started.
So where does the verb to wank come from?
Best Answer
I would say it has onomatopeic roots.
Firstly, this isn't the only word for masturbation to have echoic roots: fap is echoic of the noise of masturbation.
Looking at the entry in the OED, some of the uses spell the word whank, and in fact one example mentions that it might be echoic:
Looking through Google books, it shows that whank is used as echoic of bird calls:
For example
Also in the wank form:
Given that the OED's earliest citation (1948, British RAF) refers to a bed, I would think that wank is echoic of the sound of bed boards or mattress springs.