The word dependant is defined as “A person who relies on another, especially a family member, for financial support”. The Canada Revenue Agency’s definition of dependant is similar but can vary for each credit.
From the TurboTax articles, you can find more information about Who Can I Claim as a Dependant on my Tax Return?
If you’re a single parent, you may be able to claim one of your children under 18 years of age, or one over 18 and deemed a dependant due to mental or physical impairment, under the Amount for an Eligible Dependent. The Amount for an Eligible Dependent is sometimes also known as the Equivalent to Spouse credit.
From this TurboTax article below, you can find more information: Who are Considered Dependants?
Thank you for choosing TurboTax.