Yearlings refer to animals that are one year old or in their second year of life. However, depending on the context, there are different synonyms for this term. For example, when referring to horses, "weanlings" are those that are between six months to a year old, while "foals" are young horses under six months old. For cattle, "heifers" or "steers" may be used to refer to animals that are one year old. Similarly, "pullets" or "cockerels" may be used to refer to yearlings of poultry. Ultimately, the appropriate synonym will depend on the specific animal and its age category.