The /ɒ/ vowel is usually spelled <o> but we also find <au> in Aussie and <a> after <w> in wad. The /u/ vowel is normally spelled <oo>, but we also find <u> in truly, <ui> in juice, <ew> in clewed or <ou> in wound.
This contrast is between a short and a long vowel, both rounded but well separated in the mouth. It is not a problem for any particular set of learners.
The only taboo word pair is con/coon.
Interesting pairs include:
The density value is 3.16%. The pairs make 75 semantic contrasts, giving a loading of 50%.
Aussie oozy Aussies oozes bob boob bobbed boobed bobbing boobing bobs boobs bobby booby bobbies boobies boggy boogie bomb boom bombed boomed bombing booming bombs booms Bonn boon bossed boost bottle Bootle Bros Bruce choler cooler cholers coolers clod clewed cod cooed col cool cols cools collie coolie collies coolies con coon cons coons cop coop copped cooped copping cooping cops coops copper Cupar copper cooper coppers coopers Copt cooped cot coot cots coots crop croup crops croups drop droop dropped drooped dropping drooping drops droops flock fluke flocks flukes from Frome hod who'd hollers hulas hop hoop hopped hooped hopping hooping hops hoops hot hoot hots hoots hotted hooted hotting hooting hotter hooter hover Hoover hovered Hoovered hovering Hoovering hovers Hoovers John June joss juice josses juices jot jute jolly Julie loch Luke lock Luke locker lucre lop loop lopped looped lopping looping lops loops loss loose losses looses lost loosed lot loot lots loots Mod mood Mods moods moss moose mosses mooses noddle noodle noddles noodles overshot overshoot oz ooze poll pool polls pools pop poop pops poops popped pooped popping pooping prod prude prods prudes Prof proof rhomb rheum rhomb room rhombs rooms rod rood rods roods Ron rune roster rooster rosters roosters rot root rots roots rotted rooted rotting rooting Scot scoot Scots scoots shod shooed shot chute shotts chutes shot shoot shots shoots slop sloop slops sloops snotty snooty snottier snootier snottiest snootiest sop soup sopped souped sopping souping sops soups sot suit sots suits stodge stooge stop stoop stopped stooped stopping stooping stops stoops swan swoon swanned swooned swanning swooning swans swoons swap swoop swapped swooped swapping swooping swaps swoops Tom tomb tot toot tots toots totted tooted totting tooting trod trued trolley truly undershot undershoot wad wooed wand wound wands wounds was woos
John Higgins, Shaftesbury, November 2009