A - Abidal: The Barcelona left-back inspired a rare show of cross-club unity when Madrid's players wore t-shirts in support of him following the news he required a liver transplant in March. He remains unavailable for Barca.
B - Blaugrana: Barca's nickname in the Catalan language, meaning 'blue and maroon'. The club are fiercely defensive of their regional heritage.
C - 'Canguelo': In recent times, the Madrid-based sports press have accused Barcelona of falling victim to 'Canguelo', which literally means being scared stiff that Real Madrid would come up behind them to steal the league title. In 2007, Fabio Capello's Madrid famously overhauled Frank Rijkaard's Barca side to snatch the title on the final day of the season, prompting accusations Barca had bottled it. This season the shoe is on the other foot.
D - Doping: Last year radio station Cadena Cope accused Barca of doping through their liaison with suspicious doctors, which the club naturally denied. Reports indicated that Real Madrid officials were behind the accusation, leading Real president Florentino Perez to phone Barca counterpart Sandro Rosell to reassure him this was not the case; however former Barca president Joan Laporta has since said that he is certain of their involvement. The station has apologised to Barca and said it was wrong, as well as paying 200,000 euros in damages.
E - Eto'o: Cameroon star Samuel arrived at Real Madrid in 1996 and made just a handful of appearances. He left Mallorca before a big move to Barca, where he spent five seasons as one of the continent's most prolific strikers. He sang an anti-Madrid song amid Camp Nou celebrations of the 2004-05 Liga title, for which he was later fined heavily by the authorities who said he was "initiating violence".
F - Figo: Portugal star Luis and Barca fan favourite made the hugely controversial move to the Bernabeu in 2000. Even a world record £37 million fee was never going to placate his former fans, who greeted his return to Catalonia by pelting various objects at him, including that infamous pig's head.
G - Giovanni: The highlight of the Brazilian striker's three years at the club was undoubtedly his winner five minutes from time in a 3-2 victory at the Bernabeu in 1997, which was followed by a rather impolite gesture aimed at the home fans. Giovanni also scored in the return fixture, a 3-0 win, as Barca claimed their 15th title and Real finished fourth.
H - Head-to-head: Of the 218 previous meetings between these two since the first in 1929, Real have won 86 times, Barca 85.
I - Iker: Real's star keeper Casillas, the undisputed home-grown 'galactico'. He is one of the great modern goalkeepers and the current holder of the World Cup and European Championship alongside his Spain team-mates.
J - Juande: When Bernd Schuster got the boot in December 2008, Real turned to Ramos, himself recently made available following his sacking from Tottenham. The former Sevilla boss was brought in on a deal until the end of the season. In May of that season, Barca won 6-2 at the Bernabeu. Ramos's contract was not renewed.
K - Kaka: The duel between Cristiano Ronaldo and Lionel Messi always hogs the attention, but Brazil playmaker Kaka is both a former World Player of the Year and one of the most expensive players ever. After enduring an injury-plagued first 18 months in Spain, his form has improved, yet he remains a substitute for Madrid.
L - Luis Enrique: Another 'defector' to straddle the great divide, this time moving to Barcelona in 1996 after spending five years at Real. The versatile Asturian went on to score four times in Clasicos against his former employers.
M - 'Manita': Barca's 5-0 hammering of Real at the Camp Nou in November 2010 had home players and fans waving their hands in the air with their fingers spread in celebration of the five goals - la manita, or 'little hand'. In the build-up to a league clash last season, an advert to promote a private health insurance company on Barcelona city buses caused a stir in Madrid as it showed five Barca players holding out their hands in a similar manner. The club moved quickly to distance themselves from the advert and accusations that they were being disrespectful to their rivals.
N - Nunez: Under the 22-year presidency of Josep Lluis, Barca enjoyed the most successful period in the club's history up to that point, founding the club's now prolific La Masia academy after Johan Cruyff's recommendation, overseeing the formation of the famous 'Dream Team' and bringing European Cup glory to the club in 1992.
O - Oleguer - The defender was perhaps one of the most fiercely pro-Catalan players ever to turn out for Barcelona, and drew criticism for expressing his far left-wing views in a book and in newspaper articles. Not a fan of Real.
P - Parera: Mauel Parera Penalla scored Barcelona's first ever Clasico goal in 1929. Rafael Morera scored twice for Real in a 2-1 win for Los Merengues.
Q - Que: Bit of a cheat this one. Real Madrid head coach Jose Mourinho has been taunted in the past by Barca fans with the words '¿Por que?', meaning why? A reference to Mourinho's rant after a Champions League Clasico last season when he 'named and shamed' the referees who he believes have favoured Barca over the years. "I can't say what I feel. I only leave one question. Why?" he said. "Why? Ovrebo, Busacca, Frisk, Stark, De Bleeckere. Why to all these people. Each semi-final always brings the same. We're talking about a fantastic football team. So why?"
R - Raul: His haul of 15 Clasico goals is second only to Alfredo di Stefano (18). His first came in 1995, his last in 2008.
S - Stoichkov: Fiery Bulgarian striker Hristo only scored once against Real in his five years at Barca, but it was a memorable one - an 87th-minute winner at the Camp Nou in September 1992.
T - Tito: Barca assistant Tito Vilanova was infamously poked in the eye by Mourinho as a Super Cup clash erupted in August 2011. David Villa was also seen to punch Mesut Ozil as players and staff from both clubs became involved in the melee.
U - Unicef: During his rather unhinged rant (see 'Q'), Mourinho also famously inferred that Barcelona's decision to carry the charity's logo on their shirt may have resulted in the club receiving preferential treatment from the authorities. Barca are now sponsored by the Qatar Foundation, but Unicef's logo remains on the back of their shirt.
V - Villarato: Over the years, conspiracy theories have abounded about biased refereeing for either team. Allegations of favouritism shown towards Real by referees during the dictatorship of Francisco Franco have given way recently to Barca being accused of having a helping hand. The theory that Barca backed the re-election of Angel Maria Villar to the presidency of the Spanish federation, while Real supported a rival candidate, has given rise to the term 'Villarato' which is used every time Madrid fans think Barca have had some kind of favourable treatment.
W - Waka-Waka: Some Real fans have taken to goading Barca defender Gerard Pique with this nonsensical line from the Shakira hit ever since he began dating the Colombian pop star. He'd probably thank them for reminding him of the fact.
X - Xavi & Xabi: Two of the best passers of the ball in the game, who manage to complement each other brilliantly for the Spanish national team - Barca's Xavi and Real's Xabi Alonso.
Y - Yogurines: A Spanish term for 'the kids'. Thiago, Isaac Cuenca and Cristian Tello at Barca could well be stars of future Clasicos for years to come.
Z - Zinedine Zidane: Scored three times against Barca, most famously in the 2002 semi-final first leg before going on the score a brilliant volleyed winner in that year's final to seal Real's ninth and most recent European Cup triumph.