In singing or speaking, a deep note, the lowest sound of the voice.

(finance, historical) A banknote issued for the convenience of travellers, being a kind of bill that is personal to the bearer, who is also given a corresponding 'letter of indication' addressed to foreign bankers.

To not know anything about something.

In order to achieve something, it is inevitable and necessary that some sacrifices must be made.

(signal processing) A bandstop filter with a narrow stopband.

plural of notch filter

I did not cause the problem. / (by extension, informal) I did not cause it (regardless of whether the subject matter is perceived as problematic).

(informal) Used to indicate that something is the case and cannot be altered even if the listener does not want it to be the case.

(music) In chanting, a note on which several syllables are sung.

(colloquial) Not at all; in no way whatsoever.