There are 14 11-letter words that start with 'sin'.
| sincereness | sincerities | sinfonietta |
| singlestick | singletrees | singularity |
| singularize | sinlessness | sinological |
| sinologists | sinsemillas | sinuosities |
| sinuousness | sinusitises | |
Note: These 14 11-letter words that start with 'sin' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with sing, sinu, sinc, sino, sine, sini, sink, sinf, sint, sinl, sinn, sins, sina, sinh.
4-letter words start with 'sin' (5)