voiced dental fricative

A voiced dental fricative is a consonant sound used in some spoken languages. It is familiar to most English-speakers as the "th" sound in "father".

The symbol in the International Phonetic Alphabet for this sound is eth, ⟨ð⟩, which was taken from the Old English and Icelandic alphabets, and which in those languages could stand for either a voiced or unvoiced (inter)dental non-sibilant fricative. Such fricatives are often called "interdental" because they are often produced with the tongue between the upper and lower teeth (as in Received Pronunciation), and not just against the back of the upper teeth, as they are with other dental consonants.