So all of you suggest that - If explicitly Blocked by the OS or firewall in the system then the port is consifered to be closed.
No... ports can never be explicitly closed, only explicitly open and filtered (which may or may not be blocked completely).

If a port has NO service explicitly using it, the port is considered CLOSED.
If a port has NO service explicitly using it AND is filtered by firewall which allows ALL traffic, the port is considered CLOSED.
If a port has NO service explicitly using it AND is filtered by firewall which allows SOME/NO traffic, the port is considered FILTERED.

If a port has a service explicitly using it, the port is considered OPEN.
If a port has a service explicitly using it AND is filtered by firewall which allows ALL traffic, the port is considered OPEN.
If a port has a service explicitly using it AND is filtered by firewall which allows SOME/NO traffic traffic, the port is considered FILTERED.

It does not matter what generation of firewall is used or anything else.

"Blocked" and "Stealth" are casual terms which fall within the set of "Filtered"

Talk about RST flags and inetd, while interesting just confuse the point... as a non-standard TCP/IP stack may not issue the correct flags, but would still fall under the rules above.

cheers,

catch