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15 Letter Words Starting With IS

There are 22 valid 15 letter words that start with IS, drawn from NWL2023, CSW24, and Words With Friends. Sorted below by score, with the single highest scorer called out.

Highest Scoring 15-Letter Words

US Scrabble (NWL)

isorhythmically - 31 points

UK Scrabble (CSW)

isorhythmically - 31 points

Words With Friends

ischiococcygeal - 34 points

15 Letter Words (22)

View all words starting with IS

Top 20 Highest-Scoring 15 Letter Words Starting With is

Point values shown for US Scrabble, UK Scrabble, and Words With Friends. The average across this full 22 word list is 74.5 combined points.

Rank Word US Scrabble UK Scrabble WWF Points Total
#1 ischiocavernous 25 25 29 79
🏆 #2 ischiococcygeal 30 30 34 94
#3 ischioneuralgia 21 21 25 67
#4 ischiovertebral 25 25 28 78
#5 ismaticalnesses 19 19 23 61
#6 isoagglutinogen 18 18 25 61
#7 isoantigenicity 21 21 24 66
#8 isobathythermal 28 28 28 84
#9 isobathythermic 30 30 30 90
#10 isoelectrically 22 22 26 70
#11 isoimmunisation 19 19 24 62
#12 isoimmunization 28 28 33 89
#13 isolationalists 15 15 18 48
#14 isomeromorphism 26 26 29 81
#15 isopelletierine 17 17 21 55
#16 isoperimetrical 21 21 25 67
#17 isopodimorphous 25 25 28 78
#18 isopropylacetic 26 26 30 82
#19 isorhythmically 31 31 31 93
#20 isosulphocyanic 27 27 31 85

Where 15 Letter Words Fit on the Board

At 15 letters, a word almost always uses your entire rack plus tiles already on the board these are realistically bingo-adjacent plays rather than everyday moves, which is why the list leans heavily on compound and suffixed forms (-nesses, -ation, -izing). If you're looking for words you can play more often, shorter lengths starting with IS will give you far more flexible options try 15 letter words starting with IS for a more practical middle ground.

Frequently Asked Questions

What is the highest-scoring 15 letter word starting with is?

ischiococcygeal — worth 94 combined points (US Scrabble: 30, UK Scrabble: 30, Words With Friends: 34).

How many 15 letter words start with is?

22 valid words, combining entries from NWL2023, CSW24, and the Words With Friends dictionary.

Are 15 letter words realistic to actually play?

Only occasionally — you'd need most of your rack plus letters already on the board to reach 15 tiles. They're worth knowing for the rare bingo-extension play, but for regular turns, shorter is words will come up far more often.