cortisol/ʹkawtisol, -zol/ noun

• obsessive-compulsive
• obsidian
• obsolesce
• obsolescent
• obsolete
• obstacle
• obstacle course
• obstacle race
• obstetric
• obstetrical
• obstetrics
• obstinate
• obstreperous
• obstruct
• obstruction
• obstructionism
• obtain
• obtest
• obtrude
• obtrusive
• obtund
• obtuse
• obverse
• obvert
• obviate