specialty · exclusively

1. Origins, structure, and basic meaning

• Structure: 専 is associated with focusing on one field or purpose; its on-reading is せん.
• Basic usage: 専門(せんもん) means a specialty or field of study, while 専用(せんよう) means dedicated or exclusive use.

2. Common pitfalls and similar expressions

• A specialist field and a designated purpose or user
  • 専門 refers to a field studied at college or the expertise of a technician repairing a machine. 専門の技術者 means a specialist technician in that field.
  • 専用ペン is a pen for a particular purpose, while 職員専用 means reserved for staff. 専用 focuses on restricting the purpose or users rather than on specialist knowledge.