Merriam-Webster's Collegiate Dictionary:
old iranian
old irish
old lady
old latin
old maid
old man
old master
old nick
old norse
old occitan
old persian
old point comfort
old prussian
old rose
old sarum
old saxon
old school
old school tie
old sledge
old style
old swedish
old testament
old welsh
old wives' tale
old world
old-fashioned
old-fashionedly
old-fashionedness
old-growth
old-line
old-maidish
old-maidishness
old-man's beard
old-school
old-shoe
old-squaw
old-time
old-timer
old-timey
old-world
oldcastle
olden
oldenbarnevelt
oldenburg
oldfangled
oldham
oldie
oldish
oldster
olduvai gorge
oldwife
ole
ole-
oleaginous
oleaginously
oleaginousness
oleander
oleandomycin
oleaster
oleate
olecranon
olefin
olefinic
oleic acid
olein
olekma
olenek
oleo
oleo-
oleograph
oleomargarine
oleoresin
oleoresinous
olestra
oleum
olfaction
olfactometer
olfactorily
olfactory
olfactory bulb
olfactory lobe
olfactory nerve
olifants
olig-
oligarch
oligarchic
oligarchical
oligarchy
oligo-
oligocene
oligochaete
oligoclase
oligodendrocyte
oligodendroglia
oligodendroglial
oligomer
oligomeric
