Longest one I have ever played was the Scotch Game: Scotch Gambit, Haxo Gambit, Sarratt Variation, Vitzthum Attack. 75 characters, 10 words.

1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Bc4 Bc5 5.Ng5 Nh6 6.Qh5.

Best move for black after this is 6...Qe7, defending the f7 pawn and attacking the vulnerable e4 pawn.

The longest I know of without having moves in the name is the Italian Game: Knight Attack, Polerio, Bishop Check, Bogoljubov, Blackburne Variation (84 characters) However, it is shortened on some other websites.

this is pretty long: Nimzowitsch Defense: Scandinavian, Bogoljubov, Heinola-Deppe Gambit
 
1.e4 Nc6 2.d4 d5 3.Nc3 e5

Modern Defense: Standard, Pterodactyl, Eastern, Rhamphorynchus, Pteranodon Sicilian Variation

thats a referance

Ruy López Opening : Marshall Attack, Modern, Main Line, Spassky Variation

I know this isnt the longest name but it just the first thing that come to my mind: Reti opening, Tennison gambit, Intercontinental Ballistic Missle variation. Not sure is it spelled right or not.

I've collected your responses. If any of them were a joke, I didn't check. Enjoy.
Recommended link: Encyclopedia of Chess Openings (ECO) Similar Link

24 Giuoco Pianissimo Deferred

39 Venna game: frankenstein-dracula variation

46 Ruy López Opening: Marshall Attack, Modern, Main Line

51 King's Indian Defense: Fianchetto, Yugoslav, Panno System

51 Giuoco Piano Game: Giuoco Pianissimo, Italian Four Knights

57 King's Indian Defense: Fianchetto, Debrecen, Classical Main Line

57 Tennison Gambit, Intercontinental Ballistic Missile Variation

57 Grunfeld Defense: Exchange Variation, Modern Exchange Variation

59 Sicilian Defense: Nyezhmetdinov-Rossolimo, Fianchetto Variation

59 Sicilian Defence: Open, Najdorf Variation, Poisoned Pawn Variation

59 Queen's Pawn Opening: Blackmar-Diemer Gambit, Rasa-Studier Gambit

60 King's Gambit Declined: Panteldakis Countergambit, Greco Variation

60 Queen's Gambit Declined: Albin Countergambit, Fianchetto Variation

60 Queen's Gambit Declined: Tartakower-Makagonov-Bondarevsky System

62 Nimzowitsch Defense: Scandinavian, Bogoljubov, Heinola-Deppe Gambit

63 King's Gambit Accepted: Lopez-Gianutio counter-gambit, Hein variation

63 Ruy López Opening : Marshall Attack, Modern, Main Line, Spassky Variation

64 King's Indian Defense: Sämisch, Bobotsov-Korchnoi-Petrosian Variation

64 Italian Game: Two Knights Defense, Polerio Defense, Bogoljubov Variation

65 Queen's Gambit Declined: Cambridge Springs Defense, Bogoljubov Variation

65 Modern Defense: Pterodactyl, Benoni Gambit Accepted, Beefeater Variation

66 Scotch Game: Scotch Gambit, Haxo Gambit, Sarratt Variation, Vitzthum Attack

67 Sicilian Defense: Najdorf Variation, Opocensky Variation, Traditional Line

67 Slav Defense: Modern, Alapin Variation, Czech, Krause, Wiesbaden, Sharp Line

67 Sicilian Defence: Open, Classical Variation, Sozin Attack, Magnus Smith Trap

68 Sicilian Defense: Hyperaccelerated Dragon, Fianchetto, Pterodactyl Defense

69 Neo-Grünfeld Defense: Classical, Original, Ultra-Delayed Exchange Variation

69 Réti Opening: Dutch, Lisitsyn, Rydel-Bloodgood, Polish Gambit, Dalesio Gambit

71 Italian Game: Knight Attack, Polerio, Bishop Check, Bogoljubov, Colman Variation

73 Queens-Pawn-Opening-Blackmar-Diemer-Vienna-Gunderam-Attack-Kampars-Gambit

75 Italian Game: Knight Attack, Polerio, Bishop Check, Bogoljubov, Blackburne Variation

75 Italian Game: Knight Attack, Polerio, Bishop Check, Bogoljubov, Blackburne Variation

75 King's Knight Variation, Giuoco Piano Game: Evans Gambit Accepted, Stone–Ware Defence

78 Modern Defense: Standard, Pterodactyl, Eastern, Rhamphorhynchus, Pteranodon Variation

78 Englund Gambit Declined: Reversed Alekhine, Reversed Krebs, Reversed Brooklyn Variation

79 Sicilian Defense: Hyperaccelerated Dragon, Fianchetto, Pterodactyl, Exchange Variation

79 Sicilian Defense, Richter-Rauzer Variation, Neo-Modern Variation, Nyezhmetdinov Attack

79 Sicilian Defense, Nyezhmetdinov-Rossolimo Attack, Fianchetto Variation, Lutikov Gambit

79 King's Knight Variation, Giuoco Piano Game: Evans Gambit Declined, Fontaine Countergambit

80 Dutch Defense, Classical Variation, Ilyin-Zhenevsky Variation, Alatortsev-Lisitsyn Line

80 Nimzowitsch Defense, Scandinavian Variation, Bogoljubow Variation, Heinola-Deppe Gambit

80 Nimzowitsch Defense, Scandinavian Variation, Bogoljubow Variation, Heinola-Deppe Gambit

81 Sicilian Defense, Lasker-Pelikan Variation, Sveshnikov Variation, Peresypkin's Sacrifice

82 Englund Gambit Declined: Reversed Alekhine, Reversed Krebs, Reversed Mokele Mbembe Variation

87 Modern Defense: Standard, Pterodactyl, Eastern, Rhamphorhynchus, Pteranodon, Sicilian Variation

88 Queen's Indian Defense: Fianchetto, Nimzowitsch Variation, Quiet, Check Variation, Intermezzo Line

88 King's Knight Variation, Giuoco Piano Game: Giuoco Pianissimo, Italian Four Knights, Canal Variation

89 The Hyperaccelerated Right Backwards Wayward Pawn Attack Transposed, Defensive Fianchetto Variation

93 King's Knight Variation, Four Knights Game: Double Spanish Variation, Symmetrical Variation, Metger Unpin

98 Sicilian Defence: Open, Scheveningen Variation, Fischer-Sozin Attack, Leonhardt Variation, Fischer Variation

99 King's Knight Variation, Four Knights Game: Spanish Variation, Rubinstein Countergambit, Henneberger Variation

119 Indian Game: King's Indian Defence, Grünfeld Defense, Schleter Variation, Makogonov Variation, Burille Variation, Opočenský Variation

137 Queen's Gambit Declined: Queen's Knight Variation, Modern Variation, Knight Defense, Cambridge Springs Defense, Bogoljubov Variation, Argentine Variation

The longest name is... Giuoco Piano Game: Giuoco Pianissimo, Italian Four Knights, Canal Variation.
 And I actually played a game of this opening

read #75 first

how about the shortest one?

Giuoco Piano Game: Giuoco Pianissimo, Italian Four Knights, Canal Variation

Tennison gambit: Intercontinental ballistic missile variation

What about the “King's Pawn Opening: King's Knight, Irish, Chicago Gambit” which is 45 letters(not including colons, commas, apostrophes, or spaces)

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