This is the 10269th most frequent French word.
inférieur
Inferior; lower in rank, status, or quality.
Here, 'inférieures' describes the positional relation of the temperatures to zero in numerical terms, indicating that they are less than zero.
Les températures sont inférieures à zéro.
The temperatures are below zero.
'Inférieur' is used to describe the hierarchical relationship between this role and the role of the director, indicating that it is ranked lower or subordinate.
Dans l'organigramme, ce rôle est inférieur à celui de directeur.
In the organizational chart, this role is lower than that of the director.
In this sentence, 'inférieure' is used as an adjective to describe the quality of the product as being lower or substandard.