CTM or Close To Male is a term for intersex individuals who can be closely described as a male, or described as 'almost male' but aren't actually male. This usually implies one has XY chromosomes, a penis or something similar to a penis, and other masculine traits while not being entirely male.
This term is important, as the term "AMAB" implies that they are assigned male at birth, which isn't always the case, wolffian implies they are not intersex, and POP implies they have a penis, which is not always the case.
Many CTM individuals who have XY chromosomes and/or other masculine traits may have ambiguous genitals, be on the agenital spectrum, or have a vagina which means they may be assigned female at birth instead. Because of this, calling them AMAB may be incorrect to properly describe their intersex condition.
History
The term CTM was coined by Cryptocrew, specifically Angel, to fill a much needed gap in language.