From volume 1 of the work.

1504003A Dictionary of Music and Musicians — CueGeorge Grove


CUE, i. e. queue, the tail of the preceding passage. Where a player or singer is reading from a separate part, and not from the score, some help is advisable to aid him in coming in correctly after the long pauses. A few notes of some other part immediately preceding the entrance of his own are therefore printed small in the stave as a guide; and this is called a cue:—

{ \override Score.TimeSignature #'stencil = ##f \time 4/4 \key bes \major \relative b' << { \mark \markup \small \italic "Alto" \override MultiMeasureRest.staff-position = #2 R1 bes4^\f bes8 bes f'4. ees8 s8 } \addlyrics { Sing ye the Lord and } \\ { \new CueVoice { \stemUp c,4 g' f ees } \addlyrics { ho -- _ _ ly } } >> }
etc.