table called 'configuration' cannot be dropped

I am running Postgresql version 9.5.14 on Ubuntu linux 16.04.
My schema defines a table called configuration.
From psql:
# \d configuration
Table "public.configuration"
Column | Type | Modifiers
----------------+------------------------+-----------
parametername | character varying(64) | not null
parametervalue | character varying(256) |
Indexes:
"configuration_pkey" PRIMARY KEY, btree (parametername)

PROBLEM:
When in psql, I type:
# DROP TABLE configuration;

psql just hangs. No further output from psql.
If I hit CTRL-C, it responds as expected with:

^CCancel request sent
ERROR: canceling statement due to user request

But why is psql stuck on the DROP statement?
Is configuration a reserved word or pre-defined table?
Do I need to rename the table?

Thanks,
Dan McCue