I have been doing some research on Macadamian Nuts for a project and I have come to a wall. I read that by definition Macadamia Nuts are not in the nut family, but I also read the latter. I am just confused about the whole, nut vs. seed thing.

Hi Jessie, you are rightly confused, because when a scientifically-defined term gets adopted in common speech, the edges around the definition get blurred.

A seed is the reproductive unit of a plant, and consists of an embryo, a food store and a protective coat.  A fruit is the maternal tissue that surrounds and protects the seed, and can take many different forms - I have definitions of over 100 distinct fruit types based on their structure and their developmental origins.

In biological terms, a nut is a hard, woody fruit which does not split naturally to expose the seed, for example a hazel nut or an acorn.  This use has been transferred in common usage to refer to any hard woody fruit or seed.  In the macadamia (as in the Brazil nut) what you get in the shops is the seed which has a woody protective coat formed from a combination of seed and maternal tiisues; the fruit which enclosed them has split and released them (in these cases the type of fruit, and how it releases the seed, dictates the fruit type, so a Brazil nut is a capsule and a macadamia nut if a follicle).

I hope this helps!