There are numerous terms in Judo that one can use. Due to Judo keeping its strong original Japanese roots, Judokas are still taught Japanese phrases. It takes a long time to learn all the colloquial terms in Judo, here's a quick guide to the important most popular ones that can get you speaking in martial arts.
Tachi-Waza (Standing technique):
Tachi-Waza is the throwing techniques of Judo; all the attempts are made from a standing position. If you ever find yourself in a Dojo and you hear your Sensei say Tachi-Waza, they are telling you to get up and do standing Judo.
Figure 1: A Judoka is performing Tachi-Waza.
Katame-Waza (Grappling techniques)
Katame-Waza is the grappling techniques of Judo and is very complicated. They are the most important moves that you have on a mat and can give you an easy win once you've mastered the skill.
Figure 2: A Judoka is performing Katame-Waza.
Sensei is most directly translated to teacher or master and is used to describe or address the Judo instructor.
Figure 3: Jigoro Kano founder of Judo was a Sensei.
Randori (Free practice)
Randori means open practice. When a Sensei calls Randori, the Judokas can carry out their Kamate-Waza on one another. Randori is to experiment with techniques and moves that you've been working on in training. You should be comfortable with your partner, so you both help each other grow without judgment.
Kata (Formal Practice)
Kata means formal training of moves and sequences. Kata is steps used to teach and learn. A Sensei might even have their very own kata that they teach you, but official Judo kata does exist which is probably what your sensei will start you off on. In essence, any pre-arranged and perfected sequence of techniques can be called a Kata, and they are used to help people learn.
Shiai is the meaning of contest in Judo, be it in the club or at events. When your sensei calls a Shiai it is an ideal situation for you to test what you've learned in a session or what you've been practicing by yourself. You can try you Judo against another person but more seriously and more competitively. Shiai is good for you to polish out your technique and develop your skill.
Figure 4: Young Judoka in the process of Shiai.
You will be doing a lot of bowing during your lifetime of Judo. You will do it before every practice starts, before you fight, when you leave the Dojo and when you’re addressing your sensei. There are two types of bows. You will do the Ritsu-rei which is the standing bow and the Zarei, a bow performed when from a kneeling position.
Figure 5: Two Judoka performing a Ristu-Rei (Standing Bow)
You will have many belts as a Judoka. They are of great significance and are a direct indication of your level of skill. You will start with a white belt and move to the more serious colors such as orange purple and brown.
Figure 6: An Obi in the process of being tied.