intractable and untameable

intricate and endless

intrusive and unmannerly

intuitive and axiomatic

invasion and aggression

invective and innuendo [invective = abusive language]

investigation and research

invidious and painful [invidious = rousing ill will, animosity]

inviolate and unscathed

invisible and silent

involuntary and automatic

irksome and distasteful

irrational and excessive

irregular and intermittent

irreligious and immoral

irremediable and eternal

irrepressible and insistent

irreverence and ingratitude

irritable and churlish [churlish = boorish or vulgar]

isolated and detached

J

jabber and chatter

jagged and multifarious

jargon and absurdity

jaundiced and jealous

jeer and scoff

jeopardy and instability

jests and sarcasms

jocular and vivacious

jostle and stumble

joy and felicity

jubilant and boastful

judgment and discretion

judicious and acute

juggled and manipulated

jumble and confuse

juncture and circumstance

jurisdiction and authority

justice and virtue

juvenile and budding

K

keen and pertinacious [pertinacious = stubbornly persistent]

kind and forbearing

kindle and intensify

kindred and analogous

kingly and autocratic

knavish and tyrannical

knowledge and conviction

known and recognized

L

labor and drudgery

lame and impotent

lamentable and depressing

languid and indifferent

large and opulent

lassitude and languor [languor = dreamy, lazy mood]

latent and lifeless

latitude and scope

laudable and deserving

laughable and grotesque

lavish and wasteful

lawlessness and violence

laxity and forbearance

laziness and profligacy

leafage and fruitage

learning and austerity

legends and traditions

legitimate and logical

leisure and tranquillity

lengthy and diffuse

lenient and sympathetic

lethargy and sloth

levity and gaiety

liberal and ample

liberty and freedom

license and laxity

likely and plausible

limited and abbreviated

listless and inert

literal and exact