Sentence:  This <WSD>cardinal number</WSD> is the smallest of the infinite <WSD>cardinal numbers</WSD>; it is the one to which Cantor has appropriated the Hebrew Aleph with the suffix 0, to distinguish it from larger infinite cardinals. Thus the name of the smallest of infinite cardinals is &alefsym;<sub>0</sub>. 
Meaning of the word marked with <WSD> tags:  A generalized kind of number used to denote the size of a set, including infinite sets.