What's the difference between opponent and oppugner?

Opponent

Definition:

(a.) Situated in front; opposite; hence, opposing; adverse; antagonistic.
(n.) One who opposes; an adversary; an antagonist; a foe.
(n.) One who opposes in a disputation, argument, or other verbal controversy; specifically, one who attacks some theirs or proposition, in distinction from the respondent, or defendant, who maintains it.

Example Sentences:

(1) Certainly, Saunders did not land a single blow that threatened to stop his opponent, although he took quite a few himself that threatened his titles in the final few rounds.
(2) The odds are that Zuckerberg will one day face an opponent that can't be bought."
(3) He has also been a vocal opponent of gay marriage, appearing on the Today programme in the run-up to the same-sex marriage bill to warn that it would "cause confusion" – and asking in a Spectator column, after it was passed, "if the law will eventually be changed to allow one to marry one's dog".
(4) He is not the only jailed or exiled opponent of the CCP.
(5) After the impact … I lost my balance, making my body unstable and falling on top of my opponent,” he said in his submission to the panel, which met on Wednesday, a day after Uruguay had beaten Italy 1-0 in a decisive group-stage match.
(6) Free speech has protected hate speech, and opponents of censorship have consistantly defended the rights of unscrupulous populists and incendiarists.
(7) Arsenal’s 10 men fall at the first hurdle against Dinamo Zagreb Read more This win, even against such feeble opponents, was celebrated, with the locals chorusing their manager’s name amid a wave of relief given so much of the team’s domestic campaign to date has been dismal.
(8) The phrase “self-inflicted blow” was one he used repeatedly, along with the word “glib” – applied to his Vote Leave opponents.
(9) His teacher was the charismatic Father Matta el-Meskin (Matthew the Poor), later to become an opponent.
(10) We have to improve our playing style and beat our opponents more easily.” Van Gaal was also careful to provide an exact statement on the England full-back Luke Shaw, who suffered an ankle injury against Arsenal.
(11) In a single letter in February 2005, Charles urged a badger cull to prevent the spread of bovine tuberculosis – damning opponents to the cull as “intellectually dishonest”; lobbied for his preferred person to be appointed to crack down on the mistreatment of farmers by supermarkets; proposed his own aide to brief Downing Street on the design of new hospitals; and urged Blair to tackle an EU directive limiting the use of herbal alternative medicines in the UK.
(12) The typical balance of power on Capitol Hill over surveillance is such that opponents of renewing Section 702 face strong political headwinds.
(13) Around the same time Kadyrov said Mikhail Khodorkovsky, the former oligarch who became an opponent of Putin and now resides in Switzerland after spending a decade in prison, was now his “personal enemy”.
(14) A number of MPs and senior party figures supported a wrecking amendment that would have robbed the motion of its primary purpose, opponents said.
(15) Facebook Twitter Pinterest Trump ‘sways malevolently’ behind Hillary Clinton Instead, he began the night by assembling a group of women in a press conference to revisit alleged sexual assaults by Bill Clinton, before confronting his opponent hardest on her private email server.
(16) But what was, perhaps, even more fun than a win in the offing was that the desperation of opponents of same-sex marriage leading up to today’s argument in Obergefell v Hodges was palpable.
(17) But pipeline opponents say that by moving beetles from the Nebraska sandhills and mowing miles of grass where the insects once lived, TransCanada has illegally begun construction on the project.
(18) Despite mounting criticism during the Duma campaign, both supporters and opponents acknowledge his perceived achievement in restoring Russia's standing in the world following Boris Yeltsin's chaotic 1990s decade.
(19) These differences in hormonal responses to the fight are attributed to the more aggressive behavior displayed by the victorious opponents (winners) over their defeated competitors (losers).
(20) Koji Uehara, the one without a beard, just picked up from where he left off in the regular season, and continued to destroy opponents.