"Now that" is a phrase that indicates a change in situation or a new development. Other words and phrases that can be used as synonyms for "now that" include "since," "in light of," "given that," and "considering that." "Since" is useful when referring to something that happened earlier in time that led to the current situation, while "in light of" and "considering that" suggest a more reflective and deliberate thought process. "Given that" is often used when there are multiple factors that contribute to a decision or action. Choosing the appropriate synonym for "now that" will depend on the context and the tone of the writing or speech.