-ујем

In Serbian, verbs ending in -ати do not all conjugate alike. While most take standard regular present tense endings (like читати → читам), verbs whose stems contain the suffix sequences -овати, the secondary imperfective suffix -ивати, or -евати (after soft consonants) belong to an alternating present pattern.

1. The Morphological Shift
Rather than simply dropping the infinitive ending -ти, the entire infinitive stem suffix sequence (-ова-, -ева-, or secondary imperfective -ива-) is replaced by the present stem extension -уј-, to which standard thematic -e- class endings attach:

• ја -ујем (e.g., пут-ова-ти → пут-уј-ем)
• ти -ујеш (e.g., путујеш)
• он / она / оно -ује (e.g., путује)
• ми -ујемо (e.g., путујемо)
• ви -ујете (e.g., путујете)
• они / оне / она -ују (e.g., путују)

Note that -евати alternates to -ујем only when it serves as the phonetic allomorph of -овати following soft consonants (such as бичевати → бичујем, царевати → царујем).

2. Aspectual Nuance
In terms of verb aspect, imperfective verbs in this class express ongoing present actions (Купујем књигу — 'I am buying a book') or recurring habits (Често путујем — 'I travel often'). Prefixed, perfective verbs (such as обрадовати or отпутовати) cannot express an action happening right now in an independent clause. Crucially, however, the suffix -ивати frequently acts as a secondary imperfectivizer on prefixed stems (e.g., perfective потписати → imperfective потписивати → потписујем; perfective доказати → imperfective доказивати → доказује). Because these derived prefixed verbs are imperfective, they regularly describe ongoing and repeated actions in the present tense.

3. Productive Loanwords
Alongside suffixes like -ирати and -исати, the suffix -овати is a productive pattern used to adapt foreign verbs into Serbian. When verbs adopt this suffix, they conjugate with -ујем (e.g., лајковати → лајкујем, стартовати → стартујем, бојкотовати → бојкотујем). Many borrowed verbs in -овати are verbs with two aspect readings (biaspectual verbs), which permits them to express ongoing actions freely in the present tense.

4. Critical Distinctions
Watch out for non-alternating verbs ending in -евати and -ивати where those letters belong to a root or to the regular suffix -ва-:
• Regular -евати verbs: Verbs where -евати is not a soft variant of -овати take regular -ам endings: певати → ја певам (never *певујем), зевати → ја зевам, and Ekavian imperfective forms like успевати → ја успевам (never *успевујем) and захтевати → ја захтевам.
• Verbs with suffix -ва- on an -i- base: When the imperfectivizing suffix -ва- is added to a stem ending in -и- (often corresponding to perfectives in -ити), the verb ends in -ивати in appearance, but conjugates regularly with -ам: умивати (from умити) → ја умивам (never *умивујем), заливати / поливати (from залити / полити) → ја заливам / поливам, покривати (from покрити) → ја покривам, and откривати → ја откривам.
• Root -ив- verbs: Where -ив- belongs to the root rather than the alternating suffix -ива-: уживати (root жив-) → ја уживам (never *уживујем), пливати (root плив-) → ја пливам (never *пливујем), and почивати → ја почивам (never *почивујем).