Masturbation

You may be looking for onanism.

Masturbation, also known as wanking, spanking, and onanism, was sexual stimulation without a partner, often—though not always—done to pornography. "Wanker" was also an insult.

Fern touched himself while watching pornography that depicted sex between a man and a woman, two women, and two men. (PROSE: A Rose by Any Other Name)

Banksy pleasured himself to a recording of Carys Fletcher and Matt Stevens having sex in his club Nightspot's bathroom: "Go on, son, with you all the way." He was alarmingly stunned to witness the Sex Gas in Carys turning Matt into a pile of dust upon orgasm. Owen Harper later recorded Gwen Cooper's kiss with Carys for later, calling it a "treat". (TV: Day One)

Rather than sleeping, Jack Harkness indulged in onanism and jigsaws. (AUDIO: Hostile Environment)

In October 2016, Mrs Linderhof caught her husband "fiddling with himself" on the stairs. (TV: For Tonight We Might Die)

Later that month, Miss Quill asked Ram Singh if there was a "great big window of porn" open as he typed out the assignment Quill marked. Ram joked he was "spanking" himself and did the whole paper using only his left hand. (TV: The Coach with the Dragon Tattoo)

In the 27th century, Bernice Summerfield noted that, through his production of literary xenopornography, her husband Jason Kane had "turned himself into a doll for aliens to pleasure themselves with", and had essentially made himself into a product to be consumed by selling pornographic accounts of his encounters "for random strangers to wank over". (PROSE: Sex Secrets of the Robot Replicants)