Synchondrosis \Syn`chon*dro"sis\, n.; pl. {Synchondroses}. [NL., fr. Gr. ?; sy`n with + ? cartilage.] (Anat.) An immovable articulation in which the union is formed by cartilage. -- {Syn`chon*dro"si*al}, a. [1913 Webster]