Central consonant
A central or medial consonant is a consonant sound that is produced when air flows across the center of the mouth over the tongue.
Examples of central consonants are the voiceless velar plosive (the "k" in the English word "skin"), the voiced alveolar fricative (the "z" in the English word "zoo") and the alveolar nasal (the "n" in the English word "plan").
A consonant in which air flows along the sides of the tongue rather than over its center is a lateral consonant.