The letters in SERIOUS make 87 words of two letters or more. The longest is SERIOUS at 7 letters, and the highest-scoring is SERIOUS at 7 points.
No other single word uses all 7 letters of SERIOUS. SERIOUS has 7 letters: 4 vowels and 3 consonants, worth 7 points before any board bonuses.
7-letter words 1
6-letter words 6
issuer6osiers6rouses6seisor6serous6sieurs6
5-letter words 18
euros5issue5osier5ourie5rises5risus5roses5roues5rouse5ruses5sieur5sires5sores5sorus5sours5souse5suers5users5
4-letter words 27
eros4euro4ires4ores4oses4ours4reis4rise4roes4rose4roue4rues4ruse4seis4sers4sire4sirs4sore4sori4sour4sous4sris4suer4sues4sure4user4uses4
3-letter words 22
ers3ess3ire3oes3ore3ors3ose3oui3our3rei3res3roe3rue3sei3ser3sir3sis3sos3sou3sri3sue3use3
2-letter words 13
er2es2is2oe2oi2or2os2re2rs2si2so2ss2us2
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.