Third wheels are individuals who are often left out when a couple is spending time together. Other synonyms for third wheels include, but are not limited to, "extra person," "odd man out," "third party," "spare wheel," "fifth wheel," "tagalong," and "gooseberry." These terms are commonly used to describe someone who feels out of place during social gatherings, dates, or events. While third wheels may feel uncomfortable or excluded, they are also typically good sports who are willing to go along with the group. All in all, whether it's an extra person on a date or a third party in a social setting, the term "third wheel" is used to describe someone who may feel like they don't quite fit in.