subvisible
adjective
sub·vis·i·ble
| \ ˌsəb-ˈvi-zə-bəl
\
\
variants:
or sub-visible
Definition of subvisible
: not visible without the aid of special instruments
subvisible particles subvisible cirrus clouds For Great Lakes fishermen, the immediate threat is not the thumb-size grown-ups but the subvisible larvae they spawn by the tens of thousands. Off the shores of Toledo and Cleveland and near Leamington, Ont., a single cubic meter of water often contains a half-million mussel larvae.— Geoffrey Cowley
Keep scrolling for more