One of a set of reference vowel qualities devised by Daniel Jones. There are two series: primary cardinal vowels 1-8, where 1-5 are unrounded and 6-8 rounded, and secondary cardinal vowels 9-16, where 9-13 are rounded and 14-16 are rounded. The front vowels are 1,9 close, 2,10 close-mid, 3,11 open-mid, 4,12 open. The back vowels are 8,16 close, 7,15 close-mid, 6,14 open-mid, 5,13 open. Apart from these, two close central vowels, unrounded and rounded (17 and 18) are sometimes added to the system.
Primary cardinal vowels shown in black.
Secondary cardinal vowels shown in red.