There are 13 11-letter words that start with 'deca'.
| decadencies | decahedrons | decalcified | 
| decalcifies | decampments | decantation | 
| decapitated | decapitates | decapitator | 
| decarbonate | decarbonize | decarburize | 
| decathletes | ||
Note: These 13 11-letter words that start with 'deca' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with decar, decal, decap, decam, decan, decad, decay, decag, decas, decat, decaf, decah.
5-letter words start with 'deca' (3)