threat B1

/θɹet/ A statement that you will hurt or punish someone, especially if they do not do what you want.

threaten B2

/ˈθrɛtən/ To say that you will hurt or punish someone, especially to make them do what you want.

intruder B2

/ənˈtɹudɚ/ Someone who enters a place or property without permission.

intrude B2

/ɪnˈtɹuːd/ To come into a place or situation where you are not wanted or invited.

intrusion B2

/ɪnˈtɹuːʒən/ The act of entering a place or situation where you are not wanted.

unobtrusive C2

/ˌʌnəbˈtɹusɪv/ Not easily noticed; quiet and not drawing attention.

protrusion C2

/pɹəˈtɹuːʒən/ Something that sticks out from a surface; a bulge.

protrude C2

/pɹəˈtɹud/ To stick out beyond a surface or edge.

abstruse C2+

/æbˈstruːs/ difficult to understand; obscure and recondite