The letters in HAPPENING make 115 words of two letters or more. The longest is HAPPENING at 9 letters, and the highest-scoring is HAPPENING at 17 points.
No other single word uses all 9 letters of HAPPENING. HAPPENING has 9 letters: 3 vowels and 6 consonants, worth 17 points before any board bonuses.
9-letter words 1
7-letter words 4
genipap12happing15heaping13napping12
6-letter words 10
5-letter words 12
aping8genip8henna8hinge9inane5nappe9neigh9panne7penna7penni7phage11pinna7
4-letter words 29
agin5epha9gaen5gain5gane5gape7gean5gien5haen7hang8heap9nape6neap6nigh8nine4nipa6page7pain6pane6pang7peag7pean6pein6peng7pian6pina6pine6ping7pipe8
3-letter words 43
age4ain3ane3ani3ape5eng4gae4gan4gap6gen4ghi7gie4gin4gip6hae6hag7hap8hen6hep8hie6hin6hip8inn3nae3nag4nah6nan3nap5nip5pah8pan5pap7pea5peg6peh8pen5pep7phi8pia5pie5pig6pin5pip7
2-letter words 16
ae2ag3ah5ai2an2eh5en2ha5he5hi5in2na2ne2pa4pe4pi4
Words are from our open word list and include some game-only words. Rude words are left out of this page; the unscrambler shows every valid word, lets you add blank tiles and filter by length.