In the absence of a definition, I'll provide one. What is a 13 letter word for vertical? Answer: perpendicular
Correspondent
acceptabilityaccommodationadvertisementalternatively
degenerationsdeterioratingdisintegratesinterregionalinterrelatinginterrelationintransigentsnonintegratednonregisteredregenerationsregistrationsreintegration
Technological, telecommuting, telemarketing, temperamental and theologically are 13 letter words. They begin with the letter t.
disagreement
Excommunicate is a 13 letter word. It begins and ends with the letter e.
Boardinghouse and brainstorming are 13 letter words. The 3rd letter is the letter a.
Some 13 letter words that start with the letter a:abbreviationsabnormalitiesacceptabilityaccessibilityaccommodationaccreditationacquaintancesacupuncturistadministratoradmissibilityadvertisementaffordabilityalgebraicallyalternativelyanniversariesannouncementsanticipationsapplicabilityappropriationapproximationarchitecturalassassinationassignabilityastonishinglyattainabilityattentivenessauthenticallyauthoritativeauthorization
Correspondent
perpendicular
encouragement
A 13-letter word that starts with "s" and ends with "s" is "schoolteachers."
quadrilateral
international
unimaginative
acceptabilityaccommodationadvertisementalternatively
degenerationsdeterioratingdisintegratesinterregionalinterrelatinginterrelationintransigentsnonintegratednonregisteredregenerationsregistrationsreintegration