Avenir means "Future" in french. The name is a refference to Paul Renners typeface Futura from 1927, wich Avenir took inspiration from. As Futura, Avenir has a perfect circular "O" and is a geometric typeface, however, in direct comparsion avenir is way more humanistic and less constructed in direct comparsion.
Avenir is a successor to many modern fonts like Gotham.
Nunito Sans shares a lot of similarities with Avenir, however it lacks its elegance. The lowercase e has a very thin vertical bar and the R reminds more of Arial than Avenir. While the overall metric is roughly the same individual letters might differ in width. For example the O is reather oval than a perfect circle but the S is wider. Another big difference are the squared dots insted of the round ones you can find at Avenir.
In terms of the metrics Hind is more close to Frutiger than it is to Avenir, however in case of the letter shaping it takes inspiration form Avenir. For example it shares the straight uppercase R and the round dots. Overall the font is more narrow and the letters end letters are ending straight not curved (eg C,G and S), also the uppercase M is not parallel.
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