In Japan, swords are called, Katanas.
Great swords or claymores. A lot of shows or games use the reference Great Swords for large two handed swords if that is what you are talking about. For example the character class Slayer uses in Tera Online are great swords.
The slayer's best friend is a two-handed greatsword loaded with damage-dealing power. Once unleashed in a roundhouse attack, it continues felling foes on all sides, and even those sneaking up from behind.
Well usually it's called a two-handed greatsword unless your someone like my Oc character I use for my stories. She's capable of using two swords that can grow to a massive greatsword that far larger then most greatswords. Like being able to slice clearly through pandemonium from the bottom all the way through the top. So yeah they are quite massive, but then again she has abnormal strength that far surpasses that of most living things.
Claymores or to other swords of history being of giant size.
It sometimes varies, but one name by which you could perhaps call ridiculously large swords is 'greatsword'. There are real-life swords that are quite large, such as the claymore and Zweihänder, but the greatsword is still the largest. That said, often times you will see anime swords that are larger than any real-life sword ever made. In such cases, there really is no word to define the class of sword they fall in, so greatsword remains the only term that can be applied to them.
Question is too general to answer properly.
There are several games and anime that use swords, some of immense size, some quite normal. Most have no name.
Some that do:
Dragon Slayer Sword
I don't know that they have a name.
They didn't exist in reality, of course, so there is no historical name for such.
One of the largest swords of the medieval period in Europe was probably the "greatsword".
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The huge manga / anime swords are far larger than those, certainly by their size much too heavy for the typical well-trained swordsman to lift, apparently (judging by their size) weighing hundreds of pounds.