This is the 605th most frequent Thai word.
สมอ
The Thai word "สมอ" means "anchor" in English.
Here, 'สมอ' is part of the term 'ต้นสมอไทย', referring to a type of tree called the Indian anchor (or Chebulic myrobalan in English).
ต้นสมอไทยเป็นต้นไม้ที่มีผลใช้ทำยาได้
The Indian anchor tree is a tree whose fruits can be used medicinally.
In this sentence, 'สมอ' refers to an 'anchor', which is the equipment used to secure a water vessel.
สมอยึดเรือไว้ไม่ให้ลอยไปตามกระแสน้ำ
The anchor holds the boat steady in the current.
In this context, 'สมอ' is used figuratively to mean 'permission' or 'clearance', likely in a poetic or less common way.