A constriction would produce a sound that would be classified as a consonant.
The term "close" /ˈkloʊs/ is recommended by the International Phonetic Association.
Close vowels are often referred to as "high" vowels, as in the Americanist phonetic tradition, because the tongue is positioned high in the mouth during articulation.
The six close vowels that have dedicated symbols in the International Phonetic Alphabet are: (IPA letters for rounded vowels are ambiguous as to whether the rounding is protrusion or compression.
Shaded areas denote articulations judged impossible.