tiltyard: (formerly) an enclosed field for tilting contests
yard: a tract of land enclosed for particular activities (sometimes paved and usually associated with buildings)
erythromycin: an antibiotic (trade name Erythrocin or E-Mycin or Ethril or Ilosone or Pediamycin) obtained from the actinomycete Streptomyces erythreus; effective against many Gram-positive bacteria and some Gram-negative