The phrase "low keyed" can refer to someone or something that is understated, subtle, or subdued. Synonyms for this phrase might include words like restrained, modest, muted, quiet, gentle, subtle, or unobtrusive. Other possibilities might include reserved, humble, demure, or discreet. These words all imply a sense of modesty or subtlety, whether in behavior, appearance, or tone. Depending on the context, other synonym options might include words like calm, serene, or tranquil, which could all describe a low-key atmosphere or mood. Overall, there are many different words that could be used as synonyms for "low keyed," all of which express a sense of subtlety, restraint, or quietude.