['laitmәuti:f]
n.
主乐调, 乐旨

[ noun ]
a melodic phrase that accompanies the reappearance of a person or situation (as in Wagner's operas)
<noun.communication>

Leitmotif \Leit"mo*tif"\, Leitmotiv
\Leit"mo*tiv"\(l[imac]t"m[-o]*t[-e]f"), n. [G., leading motive.]
1. (Mus.) a guiding theme; in Wagnerian opera, a marked
melodic phrase or short musical passage which always
accompanies the reappearance of a certain person,
situation, abstract idea, or allusion in the course of the
play; a sort of musical label. Also called {Leading
motive}.
[1913 Webster +PJC]

2. a recurring theme in the activities of a person or group.
[PJC]

Leading \Lead"ing\, a.
Guiding; directing; controlling; foremost; as, a leading
motive; a leading man; a leading example. -- {Lead"ing*ly},
adv.

{Leading case} (Law), a reported decision which has come to
be regarded as settling the law of the question involved.
--Abbott.

{Leading motive} [a translation of G. leitmotif] (Mus.), a
guiding theme; in the musical drama of Wagner, a marked
melodic phrase or short passage which always accompanies
the reappearance of a certain person, situation, abstract
idea, or allusion in the course of the play; a sort of
musical label. Also called {leitmotif} or {leitmotiv}.

{Leading note} (Mus.), the seventh note or tone in the
ascending major scale; the sensible note.

{Leading question}, a question so framed as to guide the
person questioned in making his reply.

{Leading strings}, strings by which children are supported
when beginning to walk.

{To be in leading strings}, to be in a state of infancy or
dependence, or under the guidance of others.

{Leading wheel}, a wheel situated before the driving wheels
of a locomotive engine.