Yes, lower is playable
...and is worth 9 points.
Found in the following dictionaries
Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)
"Lower" Definition
noun
A dark and ominous look: the lower of thunderheads.
A threatening, sullen, or angry look.
adjective
Below another in rank, position, or authority.
Biology Less advanced in organization or evolutionary development.
Denoting the larger and usually more representative house of a bicameral legislature.
Geology & Archaeology Relating to or being an earlier or older division of the period named.
Physically situated below a similar or comparable thing: a lower shelf.
verb-intransitive
To appear dark or threatening, as the sky.
To become less; diminish: The temperature has lowered gradually this month.
To look angry, sullen, or threatening. See Synonyms at frown.
To move down: Her hand lowered.
verb-transitive
To let, bring, or move down to a lower level.
To reduce in standing or respect.
To reduce in value, degree, or quality.
verb
To be or become dark, gloomy, and threatening .
To depress as to direction .
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