The word functional is an adjective. Functional means (1) designed for or capable of a particular function or use.
Functional is also an adjective that means (1) (of e.g. a machine) performing or capable of performing.
Functional is also an adjective that means (1) involving or affecting function rather than physiology.
Functional is also an adjective that means (1) designed for or adapted to a function or use, (2) fit or ready for use or service.
Functional is also an adjective that means (1) relating to or based on function especially as opposed to structure.
The following articles and web pages elaborate on the word functional.
Home Office Planning
Many people work from home and good planning is key to a functional home office. Learn more about planning an attractive and organized home office.
Furniture comprises functional and decorative articles that meet our seating, sleeping, and storage requirements. This furniture portfolio includes a series of videos that are related to both residential and institutional furniture.
David Burgess is a well-known maker of violins, violas, and cellos. He has established a large body of expert consensus about the tonal, artistic, and functional merit of his stringed instruments.
https://www.burgessviolins.com/
The following digital image illustrates the word functional.