(organic chemistry) Any of a group of cytotoxic polyacetylenes extracted from marine sponges of the family Petrosiidae

(idiomatic) Not disturbed or upset by. / (idiomatic) Not menacing or hostile toward.

tone, tension or pressure

(organic chemistry) Hypothetically, one of the Platonic hydrocarbons, C₄H₄, having the carbon atoms at the vertices of a tetrahedron; has not yet been synthesized, and would be very unstable.