quadrilateral
equadilateral
oblong; such as an oval or rectangle
Excommunicate is a 13 letter word. It begins and ends with the letter e.
Base of a triangle or breadth of a rectangle
Boardinghouse and brainstorming are 13 letter words. The 3rd letter is the letter a.
In the absence of a definition, I'll provide one. What is a 13 letter word for vertical? Answer: perpendicular
oblong.
Some 13 letter words that start with the letter a:abbreviationsabnormalitiesacceptabilityaccessibilityaccommodationaccreditationacquaintancesacupuncturistadministratoradmissibilityadvertisementaffordabilityalgebraicallyalternativelyanniversariesannouncementsanticipationsapplicabilityappropriationapproximationarchitecturalassassinationassignabilityastonishinglyattainabilityattentivenessauthenticallyauthoritativeauthorization
What is another word for rectangle?
Correspondent
perpendicular
The Welsh word for 'rectangle' is petryal.