Quadrilateral, (four-sided figure)
A 13-letter word that starts with "s" and ends with "s" is "schoolteachers."
international
Excommunicate is a 13 letter word. It begins and ends with the letter e.
advertisementaccompanimentacupuncturistapportionment
Senselessness
Presbyterians
televangelist?
incrimination
lethargically
oceanographer
exponentially, entertainment
13-letter words that start with W include: wheelbarrowed, whitewashings...