a. (Biol.) Between septa; as, the interseptal spaces or zones, between the transparent, or septal, zones in striated muscle; the interseptal chambers of a shell, or of a seed vessel. [ 1913 Webster ]
a. 1. Situated between teeth; as, an interdental space, the space between two teeth in a gear wheel. [ 1913 Webster ]
2. (Phon.) Formed between the upper and lower teeth; as, interdental consonants. [ 1913 Webster ]