mac·ro·lide 
(măkrō-līd)
(măkrō-līd)n.
A class of antibiotics that are produced by certain actinomycetes of the genus Streptomyces, are characterized by a large lactone ring linked to one or more sugars, and act by inhibiting protein synthesis.
[German Makrolid : makro-, macro- + L(acton), lactone + -id, -ide.]