The phrase "apply sparingly" typically refers to using something in small amounts or with discretion. Some synonyms for this phrase might include, "use judiciously," "moderate usage," "restricted application," "economical use," or "frugal dispensation." Other synonyms could include phrases like "use with care" or "use conservatively." Additionally, certain words like "minimalist" or "restrained" might convey a similar sentiment. Ultimately, the phrase "apply sparingly" is a versatile one with many possible synonyms depending on the context in which it is used. Whether describing the use of resources, product application, or personal behaviors, these synonyms can help convey a message of discretion and restraint.