थकना (thaknaa)

verb A single-sense verb meaning 'to get tired, to become exhausted' -- describes the physical/mental state of fatigue setting in.
Sense 1 : to become tired, exhausted
verb, intransitive
Synonyms: थक जाना (thak jaanaa, common compound-verb form used in most everyday speech)
Frequency: high
Cultural Note: You'll hear थक गया (thak gayaa) constantly at the end of a long day, a workout, or a crowded Delhi metro ride -- it's the default way to announce 'I'm exhausted.' Note the adjective थका हुआ (thakaa huaa, 'tired') is built directly from this verb's perfective participle, so once you know थकना you can recognize that description everywhere.
Common Mistakes: 1) Learners often mark the subject with ने (ne) by reflex since it is a past-tense verb, but थकना (thaknaa) is intransitive and never takes ने -- say मैं थक गया (main thak gayaa, 'I got tired'), not मैंने थका। 2) In natural speech this verb almost always appears with जाना (jaanaa) as थक जाना (thak jaanaa) to mark the completed onset of tiredness; the bare form थका (thakaa) alone can sound like an adjective (tired) rather than the event of becoming tired.
Sample Sentences:
आज मैं बहुत थक गया हूँ। I'm very tired today.
(aaj main bahut thak gayaa hoon।)
Register: Casual -- Mood: Indicative -- Aspect: Perfective -- Tense: Present -- Voice: Active
मेट्रो में इतनी भीड़ थी कि मैं थक गई। There was so much crowd in the metro that I got tired.
(metro men itnii bhiid thii ki main thak gaii।)
Register: Casual -- Mood: Indicative -- Aspect: Perfective -- Tense: Past -- Voice: Active
वह पूरे दिन काम करते-करते थक जाता है। He gets tired from working all day.
(vah poore din kaam karte-karte thak jaataa hai।)
Register: Neutral -- Mood: Indicative -- Aspect: Habitual -- Tense: Present -- Voice: Active
थोड़ा आराम कर लो, नहीं तो थक जाओगे। Rest a little, or else you'll get tired.
(thodaa aaraam kar lo, nahiin to thak jaaoge।)
Register: Casual -- Mood: Indicative -- Tense: Future -- Voice: Active
मत थको, अभी तो रास्ता बाकी है। Don't get tired, there's still a long way to go.
(mat thako, abhii to raastaa baakii hai।)
Register: Casual -- Mood: Imperative -- Voice: Active
अगर वह इतनी दौड़ लगाता तो जरूर थक जाता। If he had run that much, he would definitely have gotten tired.
(agar vah itnii daud lagaataa to jaroor thak jaataa।)
Register: Neutral -- Mood: Counterfactual -- Aspect: Habitual -- Voice: Active
लगता है वह सारा दिन काम करके थक चुका है। It seems he's already tired from working all day.
(lagtaa hai vah saaraa din kaam karke thak chukaa hai।)
Register: Neutral -- Mood: Indicative -- Tense: Present -- Voice: Active
बच्चे खेल-खेल कर थक गए और सो गए। The kids got tired from playing and fell asleep.
(bachche khel-khel kar thak gae aur so gae।)
Register: Neutral -- Mood: Indicative -- Aspect: Perfective -- Tense: Past -- Voice: Active
मुझे डर है कि लंबी यात्रा में बच्चे थक जाएँगे। I'm afraid the children will get tired during the long journey.
(mujhe dar hai ki lambii yaatraa men bachche thak jaaenge।)
Register: Neutral -- Mood: Subjunctive -- Tense: Future -- Voice: Active
व्यायाम करते समय शरीर थकता है, लेकिन मन तेज़ होता है। The body gets tired while exercising, but the mind becomes sharper.
(vyaayaam karte samay shariir thaktaa hai, lekin man tez hotaa hai।)
Register: Formal -- Mood: Indicative -- Aspect: Habitual -- Tense: Present -- Voice: Active
थकते-थकते भी उसने अपना काम पूरा किया। Even as he grew tired, he finished his work.
(thakte-thakte bhii usne apnaa kaam pooraa kiyaa।)
Register: Literary -- Mood: Indicative -- Aspect: Habitual -- Tense: Past -- Voice: Active
Morphology
Verb
infinitive: थकना (thaknaa)
infinitive oblique: थकने (thakne)
habitual/simple (sg.m): थकता (thaktaa)
habitual/simple (pl.m): थकते (thakte)
habitual/simple (sg.f): थकती (thaktii)
habitual/simple (pl.f): थकतीं (thaktiin)
continuous (sg.m): थक रहा (thak rahaa)
continuous (pl.m): थक रहे (thak rahe)
continuous (sg.f): थक रही (thak rahii)
continuous (pl.f): थक रहीं (thak rahiin)
perfective (sg.m): थका (thakaa)
perfective (pl.m): थके (thake)
perfective (sg.f): थकी (thakii)
perfective (pl.f): थकीं (thakiin)
imperative (informal): थक (thak)
imperative (neutral): थको (thako)
imperative (formal): थकिए (thakie)
future (1sg.m): थकूँगा (thakoongaa)
future (1sg.f): थकूँगी (thakoongii)
future (1pl.m): थकेंगे (thakenge)
future (1pl.f): थकेंगी (thakengii)
future (2sg.m): थकेगा (thakegaa)
future (2sg.f): थकेगी (thakegii)
future (2pl.m): थकोगे (thakoge)
future (2pl.f): थकोगी (thakogii)
future (3sg.m): थकेगा (thakegaa)
future (3sg.f): थकेगी (thakegii)
future (3pl.m): थकेंगे (thakenge)
future (3pl.f): थकेंगी (thakengii)
subjunctive (1sg): थकूँ (thakoon)
subjunctive (1pl): थकें (thaken)
subjunctive (2sg): थके (thake)
subjunctive (2pl): थको (thako)
subjunctive (3sg): थके (thake)
subjunctive (3pl): थकें (thaken)