The word "sick in" is often used to describe a feeling of discomfort or nausea in the stomach. Synonyms for the phrase might include terms like "queasy," "nauseous," "unsettled," or "upset." These words all connote a sense of physical unease or discomfort, often caused by indigestion, anxiety, or illness. There are many other phrases that might be used as synonyms for "sick in," depending on the context and intended meaning of the speaker. Some alternative word choices might include "feeling unwell," "having a stomachache," or "experiencing digestive distress." In general, when looking for synonyms, it's important to consider the nuances of meaning that each term carries and select the one that is most appropriate for the specific situation at hand.