Well the only Final Fantasy games I've played are the GBA versions of I & II, the DS version of III, and the SNES version of IV (w/ Namingway Edition patch). So I don't know how the stat terminology changes in later installments. But what I do know is, I genuinely thought that "Magic" meant something along the lines of "Magic Strength", and that "Magic Defense" actually meant "Magic Defense" (like Special Defense in Pokémon), but as Vanya informed me that's not actually what those stats mean. If it's that huge of a deal for some people, I'll gladly make an "official terms" patch at the end
To the best of my knowledge despite the localizations using different terms due to different teams working on the various titles the original Japanese versions of the games are all much more consistent in their terminology. This game being one of the few exceptions because the Magic Power stat was new and the Magic Defense stat was not displayed in the first game.
To help clarify things a little further as far the actual mechanics of the game goes here is a more detailed explanation.
No Magic stat to determine MP as the game used spell charges that are gained on a predetermined table for each job.
"Magic Defense" was not displayed anywhere in the game.
Note that there is no official name for this stat in the original game for NES.
Each job had a set starting "Magic Defense" and a set increase per level up.
Fighter/Knight - 15 (+3 per level)
Thief/Ninja - 15 (+2 per level)
Black Belt/Master - 10 (+4 per level for BB; +1 per level for MA) <--- These are probably reversed from their original intention.
Red Mage/Red Wizard - 20 (+2 per level)
White Mage/White Wizard - 20 (+2 per level)
Black Mage/Black Wizard - 20 (+2 per level)
The function of "Magic Defense" was to reduce the chances of status attacks and status spells from enemies from causing their intended status ailments.
However, it worked differently for damage causing spells.
And this is where some confusion may arise for localizers.
Up until this point you could happily localize this stat as "Magic Evade", but when it comes to attack spells rather than prevent damage altogether it makes it harder for them to do what is, for all intents and purposes, a critical hit.
It is almost exactly like the saving throw mechanic in many pen-and-ink RPGs such as Dungeons & Dragons.
If you get hit by a spell that does damage the "saving throw roll" is used to determine if the spell does 2x damage and your "Magic Defense" is added to make it easier to prevent.
As I stated before the "Magic" stat in this game determines the player's max MP instead of using a table for set increases.
This is because FF2 does not use a level up system at all.
This is THE ONLY game in the entire series that has a "Magic" stat that determines max MP AFAIK.
Most of the other games either use a spell charge system like FF1, a look up table for fixed values at level up, or have an MP growth algorithm.
"Magic Defense" here works much the same way as it does in FF1 except that it is closer to how the Evade stat works.
The reason for this is that unlike FF1 spells now can have a number of "hits" that can be calculated independently like physical attacks do.
These "hits" can determine damage or what specific effects a given casting will apply to the target.
For damage causing spells the base number of hits will always apply to the target without fail.
In addition to the base hit the casting gets a number of hit rolls based on the caster's Spirit or Intelligence.
The target's "Magic Defense" makes these extra hit rolls more difficult.
All in all it's a more complex way to do what FF1 did.
Again, this is THE ONLY game in the series that uses this naming convention for this stat.
Pretty much every other game separates "Magic Defense" from "Magic Evade".
Like in FF1 as a localizer you would have to come up with a name that is neither magic evasion nor magic defense because depending on the situation it could be either one.
Here are the literal translations from the first 4 games in the series.
KEY - > Earliest Official Source = Original Romanization = Literal Translation
> MAGIC = mahou = magic. (spell charges)
> ABSORB = bougyo = defense.
> EVADE % = kaihi ritsu = evasion rate.
> "Magic Defense" not named.
> MP = MP = Magic Points. (magic points)
> M.Pwr = maryoku = magical power.
> Absorb = bougyo = defense.
> Evade% = kaihi ritsu = evasion rate.
> Mgc.Res = mahou bougyo = magic defense.
> MP = MP = Magic Points. (spell charges)
> Def. = bougyo = defense.
> Evade = kaihi ritsu = evasion rate.
> M. Def. = mahou bougyo = magic defense.
> M. Evade = mahou kaihi ritsu = magic evasion rate.
> MP = MP = Magic Points. (magic points)
> Defense = bougyo = defense.
> Defense% = kaihi ritsu = evasion rate.
> Mag Def = mahou bougyo = magic defense.
> Mag Def% = mahou kaihi ritsu = magic evasion rate.
I hope that clears things up some more.