  In early-type Be stars, groups of nonradial pulsation (NRP) modes with
numerically related frequencies may be instrumental for the release of excess
angular momentum through mass-ejection events. Difference and sum/harmonic
frequencies often form additional groups. The goal of this study is to find out
whether a similar frequency pattern occurs in the cooler third-magnitude
B7-8\,IIIe shell star $\nu$ Pup. Time-series analyses are performed of space
photometry with BRITE-Constellation (2015, 2016/17, and 2017/18), SMEI
(2003--011), and Hipparcos (1989-1993). Two IUE SWP and 27 optical echelle
spectra spanning 20 years were retrieved from various archives. The optical
spectra exhibit no anomalies or well-defined variabilities. A magnetic field
was not detected. All three photometry satellites recorded variability near
0.656 c/d which is resolved into three features separated by ~0.0021 c/d. First
harmonics form a second frequency group, also spaced by ~0.0021 c/d. The
frequency spacing is very nearly but not exactly equidistant. Variability near
0.0021 c/d was not detected. The long-term frequency stability could be used to
derive meaningful constraints on the properties of a putative companion star.
The IUE spectra do not reveal the presence of a hot subluminous secondary.
$\nu$\,Pup is another Be star exhibiting an NRP variability pattern with
long-term constancy and underlining the importance of combination frequencies
and frequency groups. The star is a good target for efforts to identify an
effectively single Be star.
