1) Between teeth 
• (a.) Situated between teeth; as, an interdental space, the space between two teeth in a gear wheel. • (a.) Formed between the upper and lower teeth; as, interdental consonants.
1. Between the teeth. ... 2. Denoting the relationship between the proximal surfaces of the teeth of the same arch. ... Origin: inter-+ L. Dens, tooth ... (05 Mar 2000) ... 
In linguistics, this term refers to any sound made by placing the tongue between the upper and lower
In`ter·den'tal adjective 1. Situated between teeth; as, an interdental space, the space between two teeth in a gear wheel. 2. (Phon.) Formed between the upper and lower teeth; as, interdental consonants. 
Type: Term Pronunciation: in′tĕr-den′tăl Definitions: 1. Between the teeth. 2. Denoting the relationship between the proximal surfaces of the teeth of the same arch.
between teeth. · articulated with the tip of the tongue between the upper and lower front teeth, as the fricatives (&thslash;) and (th) of thy and thigh.