There are 10 14-letter words that start with 'mac'.
| machicolations | machineability | 
| macroaggregate | macroeconomics | 
| macroevolution | macroglobulins | 
| macromolecular | macromolecules | 
| macronutrients | macrostructure | 
Note: These 10 14-letter words that start with 'mac' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with macr, mach, maca, mace, macu, mack, macc, maci, macl, maco, macs.
4-letter words start with 'mac' (4)