Cryptocurrencies are just the collective term for both altcoins and bitcoin. And whether you consider bitcoin outdated, there is a massive gap between bitcoin and every other coin (coinmarketcap from yesterday):
Name Market Cap Volume (24h)
Bitcoin $ 3,300,989,269 $ 17,898,000
Ripple Ripple $ 195,495,080 $ 1,409,630
Litecoin $ 56,792,579 $ 626,938
Dash $ 15,160,661 $ 34,191
Stellar $ 12,840,329 $ 43,370
Dogecoin $ 11,838,137 $ 178,075
Nxt $ 10,795,969 $ 212,975
BitShares $ 10,082,123 $ 75,738
MaidSafeCoin $ 8,190,701 $ 8,394
BanxShares $ 7,509,542 $ 13,836
Peercoin $ 7,429,548 $ 126,694
Monero $ 4,104,122 $ 95,280
Namecoin $ 3,908,745 $ 25,407
Bytecoin $ 3,803,262 $ 6,957
Infinitecoin $ 3,188,527 $ 32,529
There is a reason why virtually every coin gets traded to- and from FIAT through bitcoin.
Besides, you use the term
alt on a regular basis too.