profound, serious, severe
conspicuous, distinct, notable, noticeable, obvious, remarkable
There was a distinct lack of urgency in his manner.

apparent, perceived, seeming
complete, sheer, total, utter
a complete lack of confidence

general, overall
a general lack of knowledge among the young

relative

by lack of
The situation was worsened by lack of communication.

for lack of
They lost the game, but not for lack of trying.

from lack of
She thought she would collapse from lack of sleep.

through lack of
I've lost those skills through lack of practice.

lack of
I couldn't hide my lack of enthusiasm.

no lack of sth
There is certainly no lack of interest in the subject.

really
completely, entirely
She completely lacks confidence.

apparently
He apparently lacked the desire to learn.

clearly, obviously
His claim clearly lacked conviction.

simply
Perhaps you simply lack the intelligence to realize just how serious this is?

otherwise
Her high-heeled shoes gave her the height she otherwise lacked.

appear to, seem to
His life seemed to lack direction.

in
What they lack in talent, they make up for in conviction.

Lack is used with these nouns as the object:
ability, acumen, agility, ambition, amenity, authority, backing, capability, capacity, charm, clarity, coherence, commitment, compassion, competence, confidence, consistency, continuity, conviction, coordination, courage, credibility, depth, detail, determination, direction, discipline, drive, education, elegance, emotion, empathy, energy, enthusiasm, essentials, experience, expertise, faith, feature, finance, flair, flexibility, focus, foresight, glamour, imagination, immediacy, immunity, inclination, independence, insight, inspiration, instinct, insurance, integrity, jurisdiction, leadership, maturity, means, merit, motivation, necessity, nerve, organization, originality, passion, patience, personality, power, precision, prestige, purpose, qualification, quality, refinement, relevance, resolution, resource, rhythm, rigour, self-assurance, self-confidence, self-control, semblance, sense, sensitivity, skill, sophistication, soul, spark, sparkle, stability, stamina, stature, strength, structure, substance, subtlety, symmetry, tact, talent, touch, training, trait, understanding, vigour, vision, vitality, warmth, will