The phrase "at certain times" can be used to refer to specific moments or occasions. However, there are several other synonyms that can be used to convey similar meanings. Some examples include "occasionally," "intermittently," "sporadically," "periodically," "from time to time," and "now and then." These words can convey a sense of unpredictability or irregularity, suggesting that the events in question occur infrequently or unexpectedly. On the other hand, words like "regularly," "frequently," and "consistently" suggest a more dependable or predictable schedule. Ultimately, the choice of synonym will depend on the context and tone of the sentence in which it appears.