Halliday (2008: 96):
By these and other such metaphoric processes, new meanings are created at the intersection of the two categories involved. A “semantic junction” takes place, and this construes new and complex semiotic entities having the features of both. For example, motion is a junction of “process”, which is the category meaning of a verb move, and “entity”, which is the category meaning of a noun, as in motion. Likewise, heat is both entity, because it is a noun, and quality, because the congruent form is hot which is adjective. The verb cause is a junction of process, because it is a verb, and logical-semantic relation, because the congruent form is so which is a conjunction.