plural of backing

(phonetics) Quality of being a back vowel.

Third-person singular simple present indicative form of back into

simple past tense and past participle of stab in the back

plural of back course

(aviation) The approach course formed by the rear lobe of the signal pattern of a localizer antenna array (the portion of the localizer signal emitted from the rear face of the antenna array), oriented in the reciprocal direction to the primary approach course (i.e., the back course - if a usable back course exists at all - will be rotated 180° from the primary course). Not all localizers produce a usable back-course signal; newer equipment radiates very little signal into the rear and side lobes, not enough to allow for a back-course approach.

(transitive) To reverse (a vehicle) from a confined space. / (intransitive) To withdraw from something one has agreed to do. / (transitive) To dare (someone) to not withdraw from a challenge.

(informal, intransitive) To relax. / To covertly pay in it the proceeds of a transaction in return for mediating it.

back to fundamental principles

(politics, chiefly Britain) A conscious return to principles such as self-respect, decency and honesty; especially the discredited policy of the Conservative government in the 1990s.