examples #5 (from im to lus)

impervious

not capable of being affected or disturbed

importunate

overly persistent in request or demand; troublesome

impregnable

very difficult to challenge or overcome; unconquerable

impeccable

perfect, with no problems or bad parts

impromptu

made or done on the spur of the moment; without being planned, organized

imperturbable

marked by extreme calm, impassivity, and steadiness; nonchalant

impasse

deadlock, a situation where no progress is possible

irreproachable

beyond criticism; faultless

internecine

of, relating to, or involving conflict within a group; destructive, deadly

dejected

depressed; disheartened

abject

extremely bad, degrading, or hopeless

interject

to insert abruptly into conversation

adjunct

something added but not essential

laborious

requiring considerable effort and time

latent

hidden, lying beneath the surface

lax

loose, careless, not strict

feckless

lacking initiative or strength of character

listless

without energy or enthusiasm

alleviate

to make something more bearable

eloquent

vividly or movingly expressive; fluent or persuasive in speaking or writing

elucidate

to make clear

luminous

clear, enlightening, shining

luminary

a person of prominence or brilliant achievement

lackluster

lacking in sheen, brilliance, or vitality

illustrious

notably or brilliantly outstanding