SUB-APICAL CONSONANT

A 'sub-apical consonant' is a consonant made by contact with the ''underside'' of the tip of the tongue. The only common sub-apical articulations are in the postalveolar to palatal region; these are called "retroflex".
However, most so-called retroflex consonants are actually apical; true sub-apical retroflexes are found in the Dravidian languages of southern India.
Occasionally the term "sublaminal" will be used for sub-apical. However, that term might be better used for rare sounds pronounced between the underside of the tongue and the floor of the mouth, such as the "sublaminal lower alveolar click" pronounced between the tongue and the lower gums, symbolized in the Extended IPA.