The beautiful handwriting on these invitations was done by professional calligraphers.

calligraphers 是名词 calligrapher 的复数形式，由词根 calli-（源自希腊语，意为"美丽"）和 -graph（源自希腊语，意为"书写"）加上后缀 -er（表示"从事...的人"）组成，字面意思是"从事美丽书写的人"，即"书法家"。