1. Having no placenta
   "monotremes and marsupials are aplacental mammals"

Antonym: placental

• peridotite
• perigee
• periglacial
• perigon
• perigonal
• perigone
• perigonium
• perigynous
• perihelion
• perijove
• peril
• Perilla
• Perilla frutescens crispa
• perilous
• perilously
• perilousness
• perilune
• perilymph
• perimeter
• perimetry
• perimysium
• perinasal
• perinatal
• perinatologist
• perinatology